linux-kernel - [PATCH] Added multiplier for APERF and MPERF counters

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Date:	Wed, 16 Sep 2015 14:52:18 +0200
From:	Lukasz Anaczkowski <lukasz.anaczkowski@...el.com>
To:	len.brown@...el.com, dasaratharaman.chandramouli@...el.com
Cc:	linux-kernel@...r.kernel.org,
	Hubert Chrzaniuk <hubert.chrzaniuk@...el.com>,
	Lukasz Anaczkowski <lukasz.anaczkowski@...el.com>
Subject: [PATCH] Added multiplier for APERF and MPERF counters

From: Hubert Chrzaniuk <hubert.chrzaniuk@...el.com>

Intel(R) Xeon Phi x200 (KNL) increments APERF/MPERF every
1024 clocks, which is different than other Intel architectures
(incremented every single clock).
It results in understated values for %Busy and Avg_MHz values,
thus multiplier for APERF/MPERF counters.

Signed-off-by: Hubert Chrzaniuk <hubert.chrzaniuk@...el.com>
Signed-off-by: Lukasz Anaczkowski <lukasz.anaczkowski@...el.com>
---
 tools/power/x86/turbostat/turbostat.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 9655cb4..1dda607 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -71,6 +71,7 @@ unsigned int extra_msr_offset32;
 unsigned int extra_msr_offset64;
 unsigned int extra_delta_offset32;
 unsigned int extra_delta_offset64;
+unsigned int aperf_mperf_multiplier = 1;
 int do_smi;
 double bclk;
 unsigned int show_pkg;
@@ -984,6 +985,8 @@ int get_counters(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 			return -3;
 		if (get_msr(cpu, MSR_IA32_MPERF, &t->mperf))
 			return -4;
+		t->aperf = t->aperf * aperf_mperf_multiplier;
+		t->mperf = t->mperf * aperf_mperf_multiplier;
 	}
 
 	if (do_smi) {
@@ -2543,6 +2546,13 @@ int is_knl(unsigned int family, unsigned int model)
 	return 0;
 }
 
+unsigned int get_aperf_mperf_multiplier(unsigned int family, unsigned int model)
+{
+	if (is_knl(family, model))
+		return 1024;
+	return 1;
+}
+
 #define SLM_BCLK_FREQS 5
 double slm_freq_table[SLM_BCLK_FREQS] = { 83.3, 100.0, 133.3, 116.7, 80.0};
 
@@ -2744,6 +2754,9 @@ void process_cpuid()
 		}
 	}
 
+	if (has_aperf)
+		aperf_mperf_multiplier = get_aperf_mperf_multiplier(family, model);
+
 	do_nhm_platform_info = do_nhm_cstates = do_smi = probe_nhm_msrs(family, model);
 	do_snb_cstates = has_snb_msrs(family, model);
 	do_pc2 = do_snb_cstates && (pkg_cstate_limit >= PCL__2);
-- 
1.8.3.1

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