Commit 7f1b11ba authored by Borislav Petkov's avatar Borislav Petkov

tools/power/turbostat: Fallback to an MSR read for EPB

Commit

  6d6501d9 ("tools/power/turbostat: Read energy_perf_bias from sysfs")

converted turbostat to read the energy_perf_bias value from sysfs.
However, older kernels which do not have that file yet, would fail. For
those, fall back to the MSR reading.

Fixes: 6d6501d9 ("tools/power/turbostat: Read energy_perf_bias from sysfs")
Reported-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Tested-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Link: https://lkml.kernel.org/r/20210127132444.981120-1-dedekind1@gmail.com
parent 8acf4178
......@@ -1834,12 +1834,15 @@ int get_mp(int cpu, struct msr_counter *mp, unsigned long long *counterp)
int get_epb(int cpu)
{
char path[128 + PATH_BYTES];
unsigned long long msr;
int ret, epb = -1;
FILE *fp;
sprintf(path, "/sys/devices/system/cpu/cpu%d/power/energy_perf_bias", cpu);
fp = fopen_or_die(path, "r");
fp = fopen(path, "r");
if (!fp)
goto msr_fallback;
ret = fscanf(fp, "%d", &epb);
if (ret != 1)
......@@ -1848,6 +1851,11 @@ int get_epb(int cpu)
fclose(fp);
return epb;
msr_fallback:
get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr);
return msr & 0xf;
}
void get_apic_id(struct thread_data *t)
......
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