Re: [PATCH] tools/power/turbostat: fix compatibility with older kernels

[Borislav Petkov <bp@suse.de>]

On Wed, Jan 27, 2021 at 09:33:46PM +0100, Borislav Petkov wrote:
> Yeah, lemme do a proper patch tomorrow.

Artem, how's that?

---

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 389ea5209a83..a7c4f0772e53 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -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)

---

Thx.

-- 
Regards/Gruss,
    Boris.

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