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1140 lines
28 KiB
1140 lines
28 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* sched.c - SPU scheduler. |
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* |
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* Copyright (C) IBM 2005 |
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* Author: Mark Nutter <[email protected]> |
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* |
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* 2006-03-31 NUMA domains added. |
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*/ |
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|
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#undef DEBUG |
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|
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#include <linux/errno.h> |
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#include <linux/sched/signal.h> |
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#include <linux/sched/loadavg.h> |
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#include <linux/sched/rt.h> |
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#include <linux/kernel.h> |
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#include <linux/mm.h> |
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#include <linux/slab.h> |
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#include <linux/completion.h> |
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#include <linux/vmalloc.h> |
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#include <linux/smp.h> |
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#include <linux/stddef.h> |
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#include <linux/unistd.h> |
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#include <linux/numa.h> |
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#include <linux/mutex.h> |
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#include <linux/notifier.h> |
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#include <linux/kthread.h> |
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#include <linux/pid_namespace.h> |
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#include <linux/proc_fs.h> |
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#include <linux/seq_file.h> |
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|
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#include <asm/io.h> |
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#include <asm/mmu_context.h> |
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#include <asm/spu.h> |
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#include <asm/spu_csa.h> |
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#include <asm/spu_priv1.h> |
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#include "spufs.h" |
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#define CREATE_TRACE_POINTS |
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#include "sputrace.h" |
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struct spu_prio_array { |
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DECLARE_BITMAP(bitmap, MAX_PRIO); |
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struct list_head runq[MAX_PRIO]; |
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spinlock_t runq_lock; |
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int nr_waiting; |
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}; |
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|
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static unsigned long spu_avenrun[3]; |
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static struct spu_prio_array *spu_prio; |
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static struct task_struct *spusched_task; |
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static struct timer_list spusched_timer; |
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static struct timer_list spuloadavg_timer; |
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|
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/* |
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* Priority of a normal, non-rt, non-niced'd process (aka nice level 0). |
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*/ |
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#define NORMAL_PRIO 120 |
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|
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/* |
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* Frequency of the spu scheduler tick. By default we do one SPU scheduler |
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* tick for every 10 CPU scheduler ticks. |
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*/ |
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#define SPUSCHED_TICK (10) |
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|
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/* |
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* These are the 'tuning knobs' of the scheduler: |
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* |
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* Minimum timeslice is 5 msecs (or 1 spu scheduler tick, whichever is |
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* larger), default timeslice is 100 msecs, maximum timeslice is 800 msecs. |
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*/ |
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#define MIN_SPU_TIMESLICE max(5 * HZ / (1000 * SPUSCHED_TICK), 1) |
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#define DEF_SPU_TIMESLICE (100 * HZ / (1000 * SPUSCHED_TICK)) |
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|
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#define SCALE_PRIO(x, prio) \ |
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max(x * (MAX_PRIO - prio) / (NICE_WIDTH / 2), MIN_SPU_TIMESLICE) |
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|
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/* |
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* scale user-nice values [ -20 ... 0 ... 19 ] to time slice values: |
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* [800ms ... 100ms ... 5ms] |
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* |
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* The higher a thread's priority, the bigger timeslices |
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* it gets during one round of execution. But even the lowest |
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* priority thread gets MIN_TIMESLICE worth of execution time. |
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*/ |
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void spu_set_timeslice(struct spu_context *ctx) |
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{ |
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if (ctx->prio < NORMAL_PRIO) |
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ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE * 4, ctx->prio); |
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else |
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ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE, ctx->prio); |
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} |
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|
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/* |
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* Update scheduling information from the owning thread. |
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*/ |
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void __spu_update_sched_info(struct spu_context *ctx) |
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{ |
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/* |
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* assert that the context is not on the runqueue, so it is safe |
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* to change its scheduling parameters. |
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*/ |
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BUG_ON(!list_empty(&ctx->rq)); |
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|
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/* |
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* 32-Bit assignments are atomic on powerpc, and we don't care about |
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* memory ordering here because retrieving the controlling thread is |
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* per definition racy. |
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*/ |
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ctx->tid = current->pid; |
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|
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/* |
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* We do our own priority calculations, so we normally want |
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* ->static_prio to start with. Unfortunately this field |
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* contains junk for threads with a realtime scheduling |
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* policy so we have to look at ->prio in this case. |
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*/ |
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if (rt_prio(current->prio)) |
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ctx->prio = current->prio; |
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else |
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ctx->prio = current->static_prio; |
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ctx->policy = current->policy; |
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|
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/* |
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* TO DO: the context may be loaded, so we may need to activate |
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* it again on a different node. But it shouldn't hurt anything |
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* to update its parameters, because we know that the scheduler |
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* is not actively looking at this field, since it is not on the |
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* runqueue. The context will be rescheduled on the proper node |
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* if it is timesliced or preempted. |
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*/ |
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cpumask_copy(&ctx->cpus_allowed, current->cpus_ptr); |
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|
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/* Save the current cpu id for spu interrupt routing. */ |
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ctx->last_ran = raw_smp_processor_id(); |
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} |
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void spu_update_sched_info(struct spu_context *ctx) |
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{ |
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int node; |
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if (ctx->state == SPU_STATE_RUNNABLE) { |
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node = ctx->spu->node; |
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|
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/* |
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* Take list_mutex to sync with find_victim(). |
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*/ |
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mutex_lock(&cbe_spu_info[node].list_mutex); |
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__spu_update_sched_info(ctx); |
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mutex_unlock(&cbe_spu_info[node].list_mutex); |
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} else { |
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__spu_update_sched_info(ctx); |
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} |
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} |
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static int __node_allowed(struct spu_context *ctx, int node) |
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{ |
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if (nr_cpus_node(node)) { |
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const struct cpumask *mask = cpumask_of_node(node); |
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if (cpumask_intersects(mask, &ctx->cpus_allowed)) |
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return 1; |
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} |
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return 0; |
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} |
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static int node_allowed(struct spu_context *ctx, int node) |
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{ |
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int rval; |
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spin_lock(&spu_prio->runq_lock); |
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rval = __node_allowed(ctx, node); |
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spin_unlock(&spu_prio->runq_lock); |
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return rval; |
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} |
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void do_notify_spus_active(void) |
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{ |
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int node; |
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|
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/* |
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* Wake up the active spu_contexts. |
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*/ |
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for_each_online_node(node) { |
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struct spu *spu; |
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mutex_lock(&cbe_spu_info[node].list_mutex); |
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list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) { |
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if (spu->alloc_state != SPU_FREE) { |
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struct spu_context *ctx = spu->ctx; |
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set_bit(SPU_SCHED_NOTIFY_ACTIVE, |
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&ctx->sched_flags); |
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mb(); |
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wake_up_all(&ctx->stop_wq); |
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} |
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} |
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mutex_unlock(&cbe_spu_info[node].list_mutex); |
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} |
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} |
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/** |
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* spu_bind_context - bind spu context to physical spu |
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* @spu: physical spu to bind to |
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* @ctx: context to bind |
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*/ |
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static void spu_bind_context(struct spu *spu, struct spu_context *ctx) |
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{ |
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spu_context_trace(spu_bind_context__enter, ctx, spu); |
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spuctx_switch_state(ctx, SPU_UTIL_SYSTEM); |
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if (ctx->flags & SPU_CREATE_NOSCHED) |
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atomic_inc(&cbe_spu_info[spu->node].reserved_spus); |
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ctx->stats.slb_flt_base = spu->stats.slb_flt; |
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ctx->stats.class2_intr_base = spu->stats.class2_intr; |
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spu_associate_mm(spu, ctx->owner); |
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spin_lock_irq(&spu->register_lock); |
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spu->ctx = ctx; |
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spu->flags = 0; |
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ctx->spu = spu; |
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ctx->ops = &spu_hw_ops; |
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spu->pid = current->pid; |
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spu->tgid = current->tgid; |
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spu->ibox_callback = spufs_ibox_callback; |
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spu->wbox_callback = spufs_wbox_callback; |
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spu->stop_callback = spufs_stop_callback; |
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spu->mfc_callback = spufs_mfc_callback; |
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spin_unlock_irq(&spu->register_lock); |
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spu_unmap_mappings(ctx); |
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spu_switch_log_notify(spu, ctx, SWITCH_LOG_START, 0); |
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spu_restore(&ctx->csa, spu); |
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spu->timestamp = jiffies; |
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ctx->state = SPU_STATE_RUNNABLE; |
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spuctx_switch_state(ctx, SPU_UTIL_USER); |
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} |
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/* |
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* Must be used with the list_mutex held. |
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*/ |
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static inline int sched_spu(struct spu *spu) |
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{ |
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BUG_ON(!mutex_is_locked(&cbe_spu_info[spu->node].list_mutex)); |
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return (!spu->ctx || !(spu->ctx->flags & SPU_CREATE_NOSCHED)); |
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} |
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static void aff_merge_remaining_ctxs(struct spu_gang *gang) |
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{ |
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struct spu_context *ctx; |
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list_for_each_entry(ctx, &gang->aff_list_head, aff_list) { |
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if (list_empty(&ctx->aff_list)) |
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list_add(&ctx->aff_list, &gang->aff_list_head); |
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} |
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gang->aff_flags |= AFF_MERGED; |
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} |
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static void aff_set_offsets(struct spu_gang *gang) |
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{ |
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struct spu_context *ctx; |
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int offset; |
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offset = -1; |
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list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list, |
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aff_list) { |
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if (&ctx->aff_list == &gang->aff_list_head) |
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break; |
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ctx->aff_offset = offset--; |
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} |
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offset = 0; |
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list_for_each_entry(ctx, gang->aff_ref_ctx->aff_list.prev, aff_list) { |
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if (&ctx->aff_list == &gang->aff_list_head) |
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break; |
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ctx->aff_offset = offset++; |
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} |
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gang->aff_flags |= AFF_OFFSETS_SET; |
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} |
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static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff, |
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int group_size, int lowest_offset) |
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{ |
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struct spu *spu; |
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int node, n; |
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/* |
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* TODO: A better algorithm could be used to find a good spu to be |
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* used as reference location for the ctxs chain. |
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*/ |
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node = cpu_to_node(raw_smp_processor_id()); |
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for (n = 0; n < MAX_NUMNODES; n++, node++) { |
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/* |
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* "available_spus" counts how many spus are not potentially |
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* going to be used by other affinity gangs whose reference |
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* context is already in place. Although this code seeks to |
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* avoid having affinity gangs with a summed amount of |
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* contexts bigger than the amount of spus in the node, |
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* this may happen sporadically. In this case, available_spus |
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* becomes negative, which is harmless. |
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*/ |
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int available_spus; |
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node = (node < MAX_NUMNODES) ? node : 0; |
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if (!node_allowed(ctx, node)) |
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continue; |
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available_spus = 0; |
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mutex_lock(&cbe_spu_info[node].list_mutex); |
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list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) { |
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if (spu->ctx && spu->ctx->gang && !spu->ctx->aff_offset |
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&& spu->ctx->gang->aff_ref_spu) |
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available_spus -= spu->ctx->gang->contexts; |
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available_spus++; |
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} |
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if (available_spus < ctx->gang->contexts) { |
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mutex_unlock(&cbe_spu_info[node].list_mutex); |
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continue; |
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} |
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list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) { |
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if ((!mem_aff || spu->has_mem_affinity) && |
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sched_spu(spu)) { |
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mutex_unlock(&cbe_spu_info[node].list_mutex); |
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return spu; |
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} |
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} |
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mutex_unlock(&cbe_spu_info[node].list_mutex); |
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} |
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return NULL; |
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} |
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static void aff_set_ref_point_location(struct spu_gang *gang) |
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{ |
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int mem_aff, gs, lowest_offset; |
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struct spu_context *ctx; |
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struct spu *tmp; |
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mem_aff = gang->aff_ref_ctx->flags & SPU_CREATE_AFFINITY_MEM; |
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lowest_offset = 0; |
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gs = 0; |
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list_for_each_entry(tmp, &gang->aff_list_head, aff_list) |
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gs++; |
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list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list, |
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aff_list) { |
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if (&ctx->aff_list == &gang->aff_list_head) |
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break; |
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lowest_offset = ctx->aff_offset; |
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} |
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gang->aff_ref_spu = aff_ref_location(gang->aff_ref_ctx, mem_aff, gs, |
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lowest_offset); |
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} |
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static struct spu *ctx_location(struct spu *ref, int offset, int node) |
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{ |
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struct spu *spu; |
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spu = NULL; |
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if (offset >= 0) { |
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list_for_each_entry(spu, ref->aff_list.prev, aff_list) { |
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BUG_ON(spu->node != node); |
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if (offset == 0) |
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break; |
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if (sched_spu(spu)) |
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offset--; |
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} |
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} else { |
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list_for_each_entry_reverse(spu, ref->aff_list.next, aff_list) { |
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BUG_ON(spu->node != node); |
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if (offset == 0) |
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break; |
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if (sched_spu(spu)) |
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offset++; |
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} |
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} |
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return spu; |
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} |
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|
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/* |
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* affinity_check is called each time a context is going to be scheduled. |
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* It returns the spu ptr on which the context must run. |
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*/ |
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static int has_affinity(struct spu_context *ctx) |
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{ |
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struct spu_gang *gang = ctx->gang; |
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if (list_empty(&ctx->aff_list)) |
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return 0; |
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|
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if (atomic_read(&ctx->gang->aff_sched_count) == 0) |
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ctx->gang->aff_ref_spu = NULL; |
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if (!gang->aff_ref_spu) { |
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if (!(gang->aff_flags & AFF_MERGED)) |
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aff_merge_remaining_ctxs(gang); |
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if (!(gang->aff_flags & AFF_OFFSETS_SET)) |
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aff_set_offsets(gang); |
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aff_set_ref_point_location(gang); |
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} |
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return gang->aff_ref_spu != NULL; |
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} |
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/** |
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* spu_unbind_context - unbind spu context from physical spu |
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* @spu: physical spu to unbind from |
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* @ctx: context to unbind |
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*/ |
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static void spu_unbind_context(struct spu *spu, struct spu_context *ctx) |
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{ |
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u32 status; |
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spu_context_trace(spu_unbind_context__enter, ctx, spu); |
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spuctx_switch_state(ctx, SPU_UTIL_SYSTEM); |
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|
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if (spu->ctx->flags & SPU_CREATE_NOSCHED) |
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atomic_dec(&cbe_spu_info[spu->node].reserved_spus); |
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|
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if (ctx->gang) |
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/* |
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* If ctx->gang->aff_sched_count is positive, SPU affinity is |
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* being considered in this gang. Using atomic_dec_if_positive |
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* allow us to skip an explicit check for affinity in this gang |
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*/ |
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atomic_dec_if_positive(&ctx->gang->aff_sched_count); |
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|
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spu_unmap_mappings(ctx); |
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spu_save(&ctx->csa, spu); |
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spu_switch_log_notify(spu, ctx, SWITCH_LOG_STOP, 0); |
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|
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spin_lock_irq(&spu->register_lock); |
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spu->timestamp = jiffies; |
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ctx->state = SPU_STATE_SAVED; |
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spu->ibox_callback = NULL; |
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spu->wbox_callback = NULL; |
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spu->stop_callback = NULL; |
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spu->mfc_callback = NULL; |
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spu->pid = 0; |
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spu->tgid = 0; |
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ctx->ops = &spu_backing_ops; |
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spu->flags = 0; |
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spu->ctx = NULL; |
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spin_unlock_irq(&spu->register_lock); |
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|
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spu_associate_mm(spu, NULL); |
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|
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ctx->stats.slb_flt += |
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(spu->stats.slb_flt - ctx->stats.slb_flt_base); |
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ctx->stats.class2_intr += |
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(spu->stats.class2_intr - ctx->stats.class2_intr_base); |
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|
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/* This maps the underlying spu state to idle */ |
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spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED); |
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ctx->spu = NULL; |
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|
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if (spu_stopped(ctx, &status)) |
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wake_up_all(&ctx->stop_wq); |
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} |
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|
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/** |
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* spu_add_to_rq - add a context to the runqueue |
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* @ctx: context to add |
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*/ |
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static void __spu_add_to_rq(struct spu_context *ctx) |
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{ |
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/* |
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* Unfortunately this code path can be called from multiple threads |
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* on behalf of a single context due to the way the problem state |
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* mmap support works. |
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* |
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* Fortunately we need to wake up all these threads at the same time |
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* and can simply skip the runqueue addition for every but the first |
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* thread getting into this codepath. |
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* |
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* It's still quite hacky, and long-term we should proxy all other |
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* threads through the owner thread so that spu_run is in control |
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* of all the scheduling activity for a given context. |
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*/ |
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if (list_empty(&ctx->rq)) { |
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list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]); |
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set_bit(ctx->prio, spu_prio->bitmap); |
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if (!spu_prio->nr_waiting++) |
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mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK); |
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} |
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} |
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|
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static void spu_add_to_rq(struct spu_context *ctx) |
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{ |
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spin_lock(&spu_prio->runq_lock); |
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__spu_add_to_rq(ctx); |
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spin_unlock(&spu_prio->runq_lock); |
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} |
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|
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static void __spu_del_from_rq(struct spu_context *ctx) |
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{ |
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int prio = ctx->prio; |
|
|
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if (!list_empty(&ctx->rq)) { |
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if (!--spu_prio->nr_waiting) |
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del_timer(&spusched_timer); |
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list_del_init(&ctx->rq); |
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|
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if (list_empty(&spu_prio->runq[prio])) |
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clear_bit(prio, spu_prio->bitmap); |
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} |
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} |
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|
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void spu_del_from_rq(struct spu_context *ctx) |
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{ |
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spin_lock(&spu_prio->runq_lock); |
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__spu_del_from_rq(ctx); |
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spin_unlock(&spu_prio->runq_lock); |
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} |
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|
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static void spu_prio_wait(struct spu_context *ctx) |
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{ |
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DEFINE_WAIT(wait); |
|
|
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/* |
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* The caller must explicitly wait for a context to be loaded |
|
* if the nosched flag is set. If NOSCHED is not set, the caller |
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* queues the context and waits for an spu event or error. |
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*/ |
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BUG_ON(!(ctx->flags & SPU_CREATE_NOSCHED)); |
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|
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spin_lock(&spu_prio->runq_lock); |
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prepare_to_wait_exclusive(&ctx->stop_wq, &wait, TASK_INTERRUPTIBLE); |
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if (!signal_pending(current)) { |
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__spu_add_to_rq(ctx); |
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spin_unlock(&spu_prio->runq_lock); |
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mutex_unlock(&ctx->state_mutex); |
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schedule(); |
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mutex_lock(&ctx->state_mutex); |
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spin_lock(&spu_prio->runq_lock); |
|
__spu_del_from_rq(ctx); |
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} |
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spin_unlock(&spu_prio->runq_lock); |
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__set_current_state(TASK_RUNNING); |
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remove_wait_queue(&ctx->stop_wq, &wait); |
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} |
|
|
|
static struct spu *spu_get_idle(struct spu_context *ctx) |
|
{ |
|
struct spu *spu, *aff_ref_spu; |
|
int node, n; |
|
|
|
spu_context_nospu_trace(spu_get_idle__enter, ctx); |
|
|
|
if (ctx->gang) { |
|
mutex_lock(&ctx->gang->aff_mutex); |
|
if (has_affinity(ctx)) { |
|
aff_ref_spu = ctx->gang->aff_ref_spu; |
|
atomic_inc(&ctx->gang->aff_sched_count); |
|
mutex_unlock(&ctx->gang->aff_mutex); |
|
node = aff_ref_spu->node; |
|
|
|
mutex_lock(&cbe_spu_info[node].list_mutex); |
|
spu = ctx_location(aff_ref_spu, ctx->aff_offset, node); |
|
if (spu && spu->alloc_state == SPU_FREE) |
|
goto found; |
|
mutex_unlock(&cbe_spu_info[node].list_mutex); |
|
|
|
atomic_dec(&ctx->gang->aff_sched_count); |
|
goto not_found; |
|
} |
|
mutex_unlock(&ctx->gang->aff_mutex); |
|
} |
|
node = cpu_to_node(raw_smp_processor_id()); |
|
for (n = 0; n < MAX_NUMNODES; n++, node++) { |
|
node = (node < MAX_NUMNODES) ? node : 0; |
|
if (!node_allowed(ctx, node)) |
|
continue; |
|
|
|
mutex_lock(&cbe_spu_info[node].list_mutex); |
|
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) { |
|
if (spu->alloc_state == SPU_FREE) |
|
goto found; |
|
} |
|
mutex_unlock(&cbe_spu_info[node].list_mutex); |
|
} |
|
|
|
not_found: |
|
spu_context_nospu_trace(spu_get_idle__not_found, ctx); |
|
return NULL; |
|
|
|
found: |
|
spu->alloc_state = SPU_USED; |
|
mutex_unlock(&cbe_spu_info[node].list_mutex); |
|
spu_context_trace(spu_get_idle__found, ctx, spu); |
|
spu_init_channels(spu); |
|
return spu; |
|
} |
|
|
|
/** |
|
* find_victim - find a lower priority context to preempt |
|
* @ctx: candidate context for running |
|
* |
|
* Returns the freed physical spu to run the new context on. |
|
*/ |
|
static struct spu *find_victim(struct spu_context *ctx) |
|
{ |
|
struct spu_context *victim = NULL; |
|
struct spu *spu; |
|
int node, n; |
|
|
|
spu_context_nospu_trace(spu_find_victim__enter, ctx); |
|
|
|
/* |
|
* Look for a possible preemption candidate on the local node first. |
|
* If there is no candidate look at the other nodes. This isn't |
|
* exactly fair, but so far the whole spu scheduler tries to keep |
|
* a strong node affinity. We might want to fine-tune this in |
|
* the future. |
|
*/ |
|
restart: |
|
node = cpu_to_node(raw_smp_processor_id()); |
|
for (n = 0; n < MAX_NUMNODES; n++, node++) { |
|
node = (node < MAX_NUMNODES) ? node : 0; |
|
if (!node_allowed(ctx, node)) |
|
continue; |
|
|
|
mutex_lock(&cbe_spu_info[node].list_mutex); |
|
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) { |
|
struct spu_context *tmp = spu->ctx; |
|
|
|
if (tmp && tmp->prio > ctx->prio && |
|
!(tmp->flags & SPU_CREATE_NOSCHED) && |
|
(!victim || tmp->prio > victim->prio)) { |
|
victim = spu->ctx; |
|
} |
|
} |
|
if (victim) |
|
get_spu_context(victim); |
|
mutex_unlock(&cbe_spu_info[node].list_mutex); |
|
|
|
if (victim) { |
|
/* |
|
* This nests ctx->state_mutex, but we always lock |
|
* higher priority contexts before lower priority |
|
* ones, so this is safe until we introduce |
|
* priority inheritance schemes. |
|
* |
|
* XXX if the highest priority context is locked, |
|
* this can loop a long time. Might be better to |
|
* look at another context or give up after X retries. |
|
*/ |
|
if (!mutex_trylock(&victim->state_mutex)) { |
|
put_spu_context(victim); |
|
victim = NULL; |
|
goto restart; |
|
} |
|
|
|
spu = victim->spu; |
|
if (!spu || victim->prio <= ctx->prio) { |
|
/* |
|
* This race can happen because we've dropped |
|
* the active list mutex. Not a problem, just |
|
* restart the search. |
|
*/ |
|
mutex_unlock(&victim->state_mutex); |
|
put_spu_context(victim); |
|
victim = NULL; |
|
goto restart; |
|
} |
|
|
|
spu_context_trace(__spu_deactivate__unload, ctx, spu); |
|
|
|
mutex_lock(&cbe_spu_info[node].list_mutex); |
|
cbe_spu_info[node].nr_active--; |
|
spu_unbind_context(spu, victim); |
|
mutex_unlock(&cbe_spu_info[node].list_mutex); |
|
|
|
victim->stats.invol_ctx_switch++; |
|
spu->stats.invol_ctx_switch++; |
|
if (test_bit(SPU_SCHED_SPU_RUN, &victim->sched_flags)) |
|
spu_add_to_rq(victim); |
|
|
|
mutex_unlock(&victim->state_mutex); |
|
put_spu_context(victim); |
|
|
|
return spu; |
|
} |
|
} |
|
|
|
return NULL; |
|
} |
|
|
|
static void __spu_schedule(struct spu *spu, struct spu_context *ctx) |
|
{ |
|
int node = spu->node; |
|
int success = 0; |
|
|
|
spu_set_timeslice(ctx); |
|
|
|
mutex_lock(&cbe_spu_info[node].list_mutex); |
|
if (spu->ctx == NULL) { |
|
spu_bind_context(spu, ctx); |
|
cbe_spu_info[node].nr_active++; |
|
spu->alloc_state = SPU_USED; |
|
success = 1; |
|
} |
|
mutex_unlock(&cbe_spu_info[node].list_mutex); |
|
|
|
if (success) |
|
wake_up_all(&ctx->run_wq); |
|
else |
|
spu_add_to_rq(ctx); |
|
} |
|
|
|
static void spu_schedule(struct spu *spu, struct spu_context *ctx) |
|
{ |
|
/* not a candidate for interruptible because it's called either |
|
from the scheduler thread or from spu_deactivate */ |
|
mutex_lock(&ctx->state_mutex); |
|
if (ctx->state == SPU_STATE_SAVED) |
|
__spu_schedule(spu, ctx); |
|
spu_release(ctx); |
|
} |
|
|
|
/** |
|
* spu_unschedule - remove a context from a spu, and possibly release it. |
|
* @spu: The SPU to unschedule from |
|
* @ctx: The context currently scheduled on the SPU |
|
* @free_spu Whether to free the SPU for other contexts |
|
* |
|
* Unbinds the context @ctx from the SPU @spu. If @free_spu is non-zero, the |
|
* SPU is made available for other contexts (ie, may be returned by |
|
* spu_get_idle). If this is zero, the caller is expected to schedule another |
|
* context to this spu. |
|
* |
|
* Should be called with ctx->state_mutex held. |
|
*/ |
|
static void spu_unschedule(struct spu *spu, struct spu_context *ctx, |
|
int free_spu) |
|
{ |
|
int node = spu->node; |
|
|
|
mutex_lock(&cbe_spu_info[node].list_mutex); |
|
cbe_spu_info[node].nr_active--; |
|
if (free_spu) |
|
spu->alloc_state = SPU_FREE; |
|
spu_unbind_context(spu, ctx); |
|
ctx->stats.invol_ctx_switch++; |
|
spu->stats.invol_ctx_switch++; |
|
mutex_unlock(&cbe_spu_info[node].list_mutex); |
|
} |
|
|
|
/** |
|
* spu_activate - find a free spu for a context and execute it |
|
* @ctx: spu context to schedule |
|
* @flags: flags (currently ignored) |
|
* |
|
* Tries to find a free spu to run @ctx. If no free spu is available |
|
* add the context to the runqueue so it gets woken up once an spu |
|
* is available. |
|
*/ |
|
int spu_activate(struct spu_context *ctx, unsigned long flags) |
|
{ |
|
struct spu *spu; |
|
|
|
/* |
|
* If there are multiple threads waiting for a single context |
|
* only one actually binds the context while the others will |
|
* only be able to acquire the state_mutex once the context |
|
* already is in runnable state. |
|
*/ |
|
if (ctx->spu) |
|
return 0; |
|
|
|
spu_activate_top: |
|
if (signal_pending(current)) |
|
return -ERESTARTSYS; |
|
|
|
spu = spu_get_idle(ctx); |
|
/* |
|
* If this is a realtime thread we try to get it running by |
|
* preempting a lower priority thread. |
|
*/ |
|
if (!spu && rt_prio(ctx->prio)) |
|
spu = find_victim(ctx); |
|
if (spu) { |
|
unsigned long runcntl; |
|
|
|
runcntl = ctx->ops->runcntl_read(ctx); |
|
__spu_schedule(spu, ctx); |
|
if (runcntl & SPU_RUNCNTL_RUNNABLE) |
|
spuctx_switch_state(ctx, SPU_UTIL_USER); |
|
|
|
return 0; |
|
} |
|
|
|
if (ctx->flags & SPU_CREATE_NOSCHED) { |
|
spu_prio_wait(ctx); |
|
goto spu_activate_top; |
|
} |
|
|
|
spu_add_to_rq(ctx); |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* grab_runnable_context - try to find a runnable context |
|
* |
|
* Remove the highest priority context on the runqueue and return it |
|
* to the caller. Returns %NULL if no runnable context was found. |
|
*/ |
|
static struct spu_context *grab_runnable_context(int prio, int node) |
|
{ |
|
struct spu_context *ctx; |
|
int best; |
|
|
|
spin_lock(&spu_prio->runq_lock); |
|
best = find_first_bit(spu_prio->bitmap, prio); |
|
while (best < prio) { |
|
struct list_head *rq = &spu_prio->runq[best]; |
|
|
|
list_for_each_entry(ctx, rq, rq) { |
|
/* XXX(hch): check for affinity here as well */ |
|
if (__node_allowed(ctx, node)) { |
|
__spu_del_from_rq(ctx); |
|
goto found; |
|
} |
|
} |
|
best++; |
|
} |
|
ctx = NULL; |
|
found: |
|
spin_unlock(&spu_prio->runq_lock); |
|
return ctx; |
|
} |
|
|
|
static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio) |
|
{ |
|
struct spu *spu = ctx->spu; |
|
struct spu_context *new = NULL; |
|
|
|
if (spu) { |
|
new = grab_runnable_context(max_prio, spu->node); |
|
if (new || force) { |
|
spu_unschedule(spu, ctx, new == NULL); |
|
if (new) { |
|
if (new->flags & SPU_CREATE_NOSCHED) |
|
wake_up(&new->stop_wq); |
|
else { |
|
spu_release(ctx); |
|
spu_schedule(spu, new); |
|
/* this one can't easily be made |
|
interruptible */ |
|
mutex_lock(&ctx->state_mutex); |
|
} |
|
} |
|
} |
|
} |
|
|
|
return new != NULL; |
|
} |
|
|
|
/** |
|
* spu_deactivate - unbind a context from it's physical spu |
|
* @ctx: spu context to unbind |
|
* |
|
* Unbind @ctx from the physical spu it is running on and schedule |
|
* the highest priority context to run on the freed physical spu. |
|
*/ |
|
void spu_deactivate(struct spu_context *ctx) |
|
{ |
|
spu_context_nospu_trace(spu_deactivate__enter, ctx); |
|
__spu_deactivate(ctx, 1, MAX_PRIO); |
|
} |
|
|
|
/** |
|
* spu_yield - yield a physical spu if others are waiting |
|
* @ctx: spu context to yield |
|
* |
|
* Check if there is a higher priority context waiting and if yes |
|
* unbind @ctx from the physical spu and schedule the highest |
|
* priority context to run on the freed physical spu instead. |
|
*/ |
|
void spu_yield(struct spu_context *ctx) |
|
{ |
|
spu_context_nospu_trace(spu_yield__enter, ctx); |
|
if (!(ctx->flags & SPU_CREATE_NOSCHED)) { |
|
mutex_lock(&ctx->state_mutex); |
|
__spu_deactivate(ctx, 0, MAX_PRIO); |
|
mutex_unlock(&ctx->state_mutex); |
|
} |
|
} |
|
|
|
static noinline void spusched_tick(struct spu_context *ctx) |
|
{ |
|
struct spu_context *new = NULL; |
|
struct spu *spu = NULL; |
|
|
|
if (spu_acquire(ctx)) |
|
BUG(); /* a kernel thread never has signals pending */ |
|
|
|
if (ctx->state != SPU_STATE_RUNNABLE) |
|
goto out; |
|
if (ctx->flags & SPU_CREATE_NOSCHED) |
|
goto out; |
|
if (ctx->policy == SCHED_FIFO) |
|
goto out; |
|
|
|
if (--ctx->time_slice && test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags)) |
|
goto out; |
|
|
|
spu = ctx->spu; |
|
|
|
spu_context_trace(spusched_tick__preempt, ctx, spu); |
|
|
|
new = grab_runnable_context(ctx->prio + 1, spu->node); |
|
if (new) { |
|
spu_unschedule(spu, ctx, 0); |
|
if (test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags)) |
|
spu_add_to_rq(ctx); |
|
} else { |
|
spu_context_nospu_trace(spusched_tick__newslice, ctx); |
|
if (!ctx->time_slice) |
|
ctx->time_slice++; |
|
} |
|
out: |
|
spu_release(ctx); |
|
|
|
if (new) |
|
spu_schedule(spu, new); |
|
} |
|
|
|
/** |
|
* count_active_contexts - count nr of active tasks |
|
* |
|
* Return the number of tasks currently running or waiting to run. |
|
* |
|
* Note that we don't take runq_lock / list_mutex here. Reading |
|
* a single 32bit value is atomic on powerpc, and we don't care |
|
* about memory ordering issues here. |
|
*/ |
|
static unsigned long count_active_contexts(void) |
|
{ |
|
int nr_active = 0, node; |
|
|
|
for (node = 0; node < MAX_NUMNODES; node++) |
|
nr_active += cbe_spu_info[node].nr_active; |
|
nr_active += spu_prio->nr_waiting; |
|
|
|
return nr_active; |
|
} |
|
|
|
/** |
|
* spu_calc_load - update the avenrun load estimates. |
|
* |
|
* No locking against reading these values from userspace, as for |
|
* the CPU loadavg code. |
|
*/ |
|
static void spu_calc_load(void) |
|
{ |
|
unsigned long active_tasks; /* fixed-point */ |
|
|
|
active_tasks = count_active_contexts() * FIXED_1; |
|
spu_avenrun[0] = calc_load(spu_avenrun[0], EXP_1, active_tasks); |
|
spu_avenrun[1] = calc_load(spu_avenrun[1], EXP_5, active_tasks); |
|
spu_avenrun[2] = calc_load(spu_avenrun[2], EXP_15, active_tasks); |
|
} |
|
|
|
static void spusched_wake(struct timer_list *unused) |
|
{ |
|
mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK); |
|
wake_up_process(spusched_task); |
|
} |
|
|
|
static void spuloadavg_wake(struct timer_list *unused) |
|
{ |
|
mod_timer(&spuloadavg_timer, jiffies + LOAD_FREQ); |
|
spu_calc_load(); |
|
} |
|
|
|
static int spusched_thread(void *unused) |
|
{ |
|
struct spu *spu; |
|
int node; |
|
|
|
while (!kthread_should_stop()) { |
|
set_current_state(TASK_INTERRUPTIBLE); |
|
schedule(); |
|
for (node = 0; node < MAX_NUMNODES; node++) { |
|
struct mutex *mtx = &cbe_spu_info[node].list_mutex; |
|
|
|
mutex_lock(mtx); |
|
list_for_each_entry(spu, &cbe_spu_info[node].spus, |
|
cbe_list) { |
|
struct spu_context *ctx = spu->ctx; |
|
|
|
if (ctx) { |
|
get_spu_context(ctx); |
|
mutex_unlock(mtx); |
|
spusched_tick(ctx); |
|
mutex_lock(mtx); |
|
put_spu_context(ctx); |
|
} |
|
} |
|
mutex_unlock(mtx); |
|
} |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
void spuctx_switch_state(struct spu_context *ctx, |
|
enum spu_utilization_state new_state) |
|
{ |
|
unsigned long long curtime; |
|
signed long long delta; |
|
struct spu *spu; |
|
enum spu_utilization_state old_state; |
|
int node; |
|
|
|
curtime = ktime_get_ns(); |
|
delta = curtime - ctx->stats.tstamp; |
|
|
|
WARN_ON(!mutex_is_locked(&ctx->state_mutex)); |
|
WARN_ON(delta < 0); |
|
|
|
spu = ctx->spu; |
|
old_state = ctx->stats.util_state; |
|
ctx->stats.util_state = new_state; |
|
ctx->stats.tstamp = curtime; |
|
|
|
/* |
|
* Update the physical SPU utilization statistics. |
|
*/ |
|
if (spu) { |
|
ctx->stats.times[old_state] += delta; |
|
spu->stats.times[old_state] += delta; |
|
spu->stats.util_state = new_state; |
|
spu->stats.tstamp = curtime; |
|
node = spu->node; |
|
if (old_state == SPU_UTIL_USER) |
|
atomic_dec(&cbe_spu_info[node].busy_spus); |
|
if (new_state == SPU_UTIL_USER) |
|
atomic_inc(&cbe_spu_info[node].busy_spus); |
|
} |
|
} |
|
|
|
static int show_spu_loadavg(struct seq_file *s, void *private) |
|
{ |
|
int a, b, c; |
|
|
|
a = spu_avenrun[0] + (FIXED_1/200); |
|
b = spu_avenrun[1] + (FIXED_1/200); |
|
c = spu_avenrun[2] + (FIXED_1/200); |
|
|
|
/* |
|
* Note that last_pid doesn't really make much sense for the |
|
* SPU loadavg (it even seems very odd on the CPU side...), |
|
* but we include it here to have a 100% compatible interface. |
|
*/ |
|
seq_printf(s, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n", |
|
LOAD_INT(a), LOAD_FRAC(a), |
|
LOAD_INT(b), LOAD_FRAC(b), |
|
LOAD_INT(c), LOAD_FRAC(c), |
|
count_active_contexts(), |
|
atomic_read(&nr_spu_contexts), |
|
idr_get_cursor(&task_active_pid_ns(current)->idr) - 1); |
|
return 0; |
|
}; |
|
|
|
int __init spu_sched_init(void) |
|
{ |
|
struct proc_dir_entry *entry; |
|
int err = -ENOMEM, i; |
|
|
|
spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL); |
|
if (!spu_prio) |
|
goto out; |
|
|
|
for (i = 0; i < MAX_PRIO; i++) { |
|
INIT_LIST_HEAD(&spu_prio->runq[i]); |
|
__clear_bit(i, spu_prio->bitmap); |
|
} |
|
spin_lock_init(&spu_prio->runq_lock); |
|
|
|
timer_setup(&spusched_timer, spusched_wake, 0); |
|
timer_setup(&spuloadavg_timer, spuloadavg_wake, 0); |
|
|
|
spusched_task = kthread_run(spusched_thread, NULL, "spusched"); |
|
if (IS_ERR(spusched_task)) { |
|
err = PTR_ERR(spusched_task); |
|
goto out_free_spu_prio; |
|
} |
|
|
|
mod_timer(&spuloadavg_timer, 0); |
|
|
|
entry = proc_create_single("spu_loadavg", 0, NULL, show_spu_loadavg); |
|
if (!entry) |
|
goto out_stop_kthread; |
|
|
|
pr_debug("spusched: tick: %d, min ticks: %d, default ticks: %d\n", |
|
SPUSCHED_TICK, MIN_SPU_TIMESLICE, DEF_SPU_TIMESLICE); |
|
return 0; |
|
|
|
out_stop_kthread: |
|
kthread_stop(spusched_task); |
|
out_free_spu_prio: |
|
kfree(spu_prio); |
|
out: |
|
return err; |
|
} |
|
|
|
void spu_sched_exit(void) |
|
{ |
|
struct spu *spu; |
|
int node; |
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|
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remove_proc_entry("spu_loadavg", NULL); |
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|
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del_timer_sync(&spusched_timer); |
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del_timer_sync(&spuloadavg_timer); |
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kthread_stop(spusched_task); |
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|
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for (node = 0; node < MAX_NUMNODES; node++) { |
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mutex_lock(&cbe_spu_info[node].list_mutex); |
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list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) |
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if (spu->alloc_state != SPU_FREE) |
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spu->alloc_state = SPU_FREE; |
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mutex_unlock(&cbe_spu_info[node].list_mutex); |
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} |
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kfree(spu_prio); |
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}
|
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|