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235 lines
5.9 KiB
235 lines
5.9 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* mm/percpu-debug.c |
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* |
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* Copyright (C) 2017 Facebook Inc. |
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* Copyright (C) 2017 Dennis Zhou <[email protected]> |
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* |
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* Prints statistics about the percpu allocator and backing chunks. |
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*/ |
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#include <linux/debugfs.h> |
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#include <linux/list.h> |
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#include <linux/percpu.h> |
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#include <linux/seq_file.h> |
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#include <linux/sort.h> |
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#include <linux/vmalloc.h> |
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#include "percpu-internal.h" |
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#define P(X, Y) \ |
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seq_printf(m, " %-20s: %12lld\n", X, (long long int)Y) |
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struct percpu_stats pcpu_stats; |
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struct pcpu_alloc_info pcpu_stats_ai; |
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static int cmpint(const void *a, const void *b) |
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{ |
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return *(int *)a - *(int *)b; |
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} |
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/* |
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* Iterates over all chunks to find the max nr_alloc entries. |
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*/ |
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static int find_max_nr_alloc(void) |
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{ |
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struct pcpu_chunk *chunk; |
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int slot, max_nr_alloc; |
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max_nr_alloc = 0; |
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for (slot = 0; slot < pcpu_nr_slots; slot++) |
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list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list) |
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max_nr_alloc = max(max_nr_alloc, chunk->nr_alloc); |
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return max_nr_alloc; |
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} |
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/* |
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* Prints out chunk state. Fragmentation is considered between |
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* the beginning of the chunk to the last allocation. |
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* |
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* All statistics are in bytes unless stated otherwise. |
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*/ |
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static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk, |
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int *buffer) |
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{ |
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struct pcpu_block_md *chunk_md = &chunk->chunk_md; |
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int i, last_alloc, as_len, start, end; |
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int *alloc_sizes, *p; |
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/* statistics */ |
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int sum_frag = 0, max_frag = 0; |
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int cur_min_alloc = 0, cur_med_alloc = 0, cur_max_alloc = 0; |
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alloc_sizes = buffer; |
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/* |
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* find_last_bit returns the start value if nothing found. |
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* Therefore, we must determine if it is a failure of find_last_bit |
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* and set the appropriate value. |
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*/ |
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last_alloc = find_last_bit(chunk->alloc_map, |
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pcpu_chunk_map_bits(chunk) - |
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chunk->end_offset / PCPU_MIN_ALLOC_SIZE - 1); |
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last_alloc = test_bit(last_alloc, chunk->alloc_map) ? |
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last_alloc + 1 : 0; |
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as_len = 0; |
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start = chunk->start_offset / PCPU_MIN_ALLOC_SIZE; |
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/* |
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* If a bit is set in the allocation map, the bound_map identifies |
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* where the allocation ends. If the allocation is not set, the |
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* bound_map does not identify free areas as it is only kept accurate |
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* on allocation, not free. |
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* |
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* Positive values are allocations and negative values are free |
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* fragments. |
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*/ |
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while (start < last_alloc) { |
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if (test_bit(start, chunk->alloc_map)) { |
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end = find_next_bit(chunk->bound_map, last_alloc, |
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start + 1); |
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alloc_sizes[as_len] = 1; |
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} else { |
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end = find_next_bit(chunk->alloc_map, last_alloc, |
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start + 1); |
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alloc_sizes[as_len] = -1; |
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} |
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alloc_sizes[as_len++] *= (end - start) * PCPU_MIN_ALLOC_SIZE; |
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start = end; |
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} |
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/* |
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* The negative values are free fragments and thus sorting gives the |
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* free fragments at the beginning in largest first order. |
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*/ |
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if (as_len > 0) { |
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sort(alloc_sizes, as_len, sizeof(int), cmpint, NULL); |
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/* iterate through the unallocated fragments */ |
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for (i = 0, p = alloc_sizes; *p < 0 && i < as_len; i++, p++) { |
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sum_frag -= *p; |
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max_frag = max(max_frag, -1 * (*p)); |
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} |
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cur_min_alloc = alloc_sizes[i]; |
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cur_med_alloc = alloc_sizes[(i + as_len - 1) / 2]; |
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cur_max_alloc = alloc_sizes[as_len - 1]; |
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} |
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P("nr_alloc", chunk->nr_alloc); |
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P("max_alloc_size", chunk->max_alloc_size); |
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P("empty_pop_pages", chunk->nr_empty_pop_pages); |
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P("first_bit", chunk_md->first_free); |
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P("free_bytes", chunk->free_bytes); |
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P("contig_bytes", chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE); |
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P("sum_frag", sum_frag); |
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P("max_frag", max_frag); |
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P("cur_min_alloc", cur_min_alloc); |
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P("cur_med_alloc", cur_med_alloc); |
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P("cur_max_alloc", cur_max_alloc); |
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seq_putc(m, '\n'); |
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} |
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static int percpu_stats_show(struct seq_file *m, void *v) |
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{ |
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struct pcpu_chunk *chunk; |
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int slot, max_nr_alloc; |
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int *buffer; |
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alloc_buffer: |
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spin_lock_irq(&pcpu_lock); |
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max_nr_alloc = find_max_nr_alloc(); |
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spin_unlock_irq(&pcpu_lock); |
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/* there can be at most this many free and allocated fragments */ |
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buffer = vmalloc(array_size(sizeof(int), (2 * max_nr_alloc + 1))); |
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if (!buffer) |
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return -ENOMEM; |
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spin_lock_irq(&pcpu_lock); |
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/* if the buffer allocated earlier is too small */ |
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if (max_nr_alloc < find_max_nr_alloc()) { |
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spin_unlock_irq(&pcpu_lock); |
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vfree(buffer); |
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goto alloc_buffer; |
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} |
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#define PL(X) \ |
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seq_printf(m, " %-20s: %12lld\n", #X, (long long int)pcpu_stats_ai.X) |
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seq_printf(m, |
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"Percpu Memory Statistics\n" |
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"Allocation Info:\n" |
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"----------------------------------------\n"); |
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PL(unit_size); |
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PL(static_size); |
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PL(reserved_size); |
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PL(dyn_size); |
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PL(atom_size); |
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PL(alloc_size); |
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seq_putc(m, '\n'); |
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#undef PL |
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#define PU(X) \ |
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seq_printf(m, " %-20s: %12llu\n", #X, (unsigned long long)pcpu_stats.X) |
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seq_printf(m, |
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"Global Stats:\n" |
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"----------------------------------------\n"); |
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PU(nr_alloc); |
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PU(nr_dealloc); |
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PU(nr_cur_alloc); |
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PU(nr_max_alloc); |
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PU(nr_chunks); |
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PU(nr_max_chunks); |
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PU(min_alloc_size); |
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PU(max_alloc_size); |
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P("empty_pop_pages", pcpu_nr_empty_pop_pages); |
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seq_putc(m, '\n'); |
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#undef PU |
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seq_printf(m, |
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"Per Chunk Stats:\n" |
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"----------------------------------------\n"); |
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if (pcpu_reserved_chunk) { |
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seq_puts(m, "Chunk: <- Reserved Chunk\n"); |
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chunk_map_stats(m, pcpu_reserved_chunk, buffer); |
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} |
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for (slot = 0; slot < pcpu_nr_slots; slot++) { |
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list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list) { |
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if (chunk == pcpu_first_chunk) |
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seq_puts(m, "Chunk: <- First Chunk\n"); |
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else if (slot == pcpu_to_depopulate_slot) |
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seq_puts(m, "Chunk (to_depopulate)\n"); |
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else if (slot == pcpu_sidelined_slot) |
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seq_puts(m, "Chunk (sidelined):\n"); |
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else |
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seq_puts(m, "Chunk:\n"); |
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chunk_map_stats(m, chunk, buffer); |
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} |
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} |
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spin_unlock_irq(&pcpu_lock); |
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vfree(buffer); |
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return 0; |
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} |
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DEFINE_SHOW_ATTRIBUTE(percpu_stats); |
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static int __init init_percpu_stats_debugfs(void) |
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{ |
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debugfs_create_file("percpu_stats", 0444, NULL, NULL, |
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&percpu_stats_fops); |
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return 0; |
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} |
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late_initcall(init_percpu_stats_debugfs);
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