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52 lines
1.1 KiB
52 lines
1.1 KiB
#include <stdio.h> |
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#include <stdlib.h> |
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#include <unistd.h> |
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#include <linux/bitops.h> |
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#include "api/fs/fs.h" |
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#include "smt.h" |
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int smt_on(void) |
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{ |
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static bool cached; |
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static int cached_result; |
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int cpu; |
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int ncpu; |
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if (cached) |
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return cached_result; |
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if (sysfs__read_int("devices/system/cpu/smt/active", &cached_result) > 0) |
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goto done; |
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ncpu = sysconf(_SC_NPROCESSORS_CONF); |
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for (cpu = 0; cpu < ncpu; cpu++) { |
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unsigned long long siblings; |
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char *str; |
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size_t strlen; |
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char fn[256]; |
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snprintf(fn, sizeof fn, |
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"devices/system/cpu/cpu%d/topology/core_cpus", cpu); |
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if (sysfs__read_str(fn, &str, &strlen) < 0) { |
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snprintf(fn, sizeof fn, |
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"devices/system/cpu/cpu%d/topology/thread_siblings", |
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cpu); |
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if (sysfs__read_str(fn, &str, &strlen) < 0) |
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continue; |
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} |
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/* Entry is hex, but does not have 0x, so need custom parser */ |
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siblings = strtoull(str, NULL, 16); |
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free(str); |
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if (hweight64(siblings) > 1) { |
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cached_result = 1; |
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cached = true; |
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break; |
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} |
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} |
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if (!cached) { |
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cached_result = 0; |
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done: |
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cached = true; |
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} |
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return cached_result; |
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}
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