mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-28 07:04:00 +08:00
de5077c4e3
Add an smt_on() function to return if SMT is enabled or disabled. Used in the next patch. Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: http://lkml.kernel.org/r/20170811232634.30465-7-andi@firstfloor.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
45 lines
845 B
C
45 lines
845 B
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/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;
|
|
}
|