linux/tools/perf/util/smt.c
Kan Liang 0ccdb8407a perf tools: Apply new CPU topology sysfs attributes
The existing "thread_siblings" and "thread_siblings_list" attribute will
be deprecated.

Use the new CPU topology sysfs attributes, "core_cpus" and
"core_cpus_list", which are synonymous with the deprecated attributes.

Check the new name first. If not available, use the deprecated name to
be compatible with old kernel.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1559688644-106558-5-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-06-10 16:20:11 -03:00

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C

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