tools/perf/util/smt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <string.h>
   3 #include "api/fs/fs.h"
   4 #include "cputopo.h"
   5 #include "smt.h"
   6
   7 bool smt_on(const struct cpu_topology *topology)
   8 {
   9         static bool cached;
  10         static bool cached_result;
  11         int fs_value;
  12
  13         if (cached)
  14                 return cached_result;
  15
  16         if (sysfs__read_int("devices/system/cpu/smt/active", &fs_value) >= 0)
  17                 cached_result = (fs_value == 1);
  18         else
  19                 cached_result = cpu_topology__smt_on(topology);
  20
  21         cached = true;
  22         return cached_result;
  23 }
  24
  25 bool core_wide(bool system_wide, const char *user_requested_cpu_list,
  26                const struct cpu_topology *topology)
  27 {
  28         /* If not everything running on a core is being recorded then we can't use core_wide. */
  29         if (!system_wide)
  30                 return false;
  31
  32         /* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
  33         if (!smt_on(topology))
  34                 return true;
  35
  36         return cpu_topology__core_wide(topology, user_requested_cpu_list);
  37 }