linux-kernel - [PATCH v3] platform/x86: intel_pmc_core: transform Pkg C-state residency from TSC ticks into microseconds

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Message-Id: <20190619082801.21699-1-harry.pan@intel.com>
Date:   Wed, 19 Jun 2019 16:28:01 +0800
From:   Harry Pan <harry.pan@...el.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     gs0622@...il.com, Harry Pan <harry.pan@...el.com>,
        Vishwanath Somayaji <vishwanath.somayaji@...el.com>,
        Andy Shevchenko <andy@...radead.org>,
        platform-driver-x86@...r.kernel.org,
        Rajneesh Bhardwaj <rajneesh.bhardwaj@...el.com>,
        Darren Hart <dvhart@...radead.org>
Subject: [PATCH v3] platform/x86: intel_pmc_core: transform Pkg C-state residency from TSC ticks into microseconds

Refer to the Intel SDM Vol.4, the package C-state residency counters
of modern IA micro-architecture are all ticking in TSC frequency,
hence we can apply simple math to transform the ticks into microseconds.
i.e.,
residency (ms) = count / tsc_khz
residency (us) = count / tsc_khz * 1000

This also aligns to other sysfs debug entries of residency counter in
the same metric in microseconds, benefits reading and scripting.

v2: restore the accidentally deleted newline, no function change.
v3: apply kernel do_div() macro to calculate division

Signed-off-by: Harry Pan <harry.pan@...el.com>

---

 drivers/platform/x86/intel_pmc_core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
index f2c621b55f49..ab798efacc85 100644
--- a/drivers/platform/x86/intel_pmc_core.c
+++ b/drivers/platform/x86/intel_pmc_core.c
@@ -24,6 +24,7 @@
 #include <asm/cpu_device_id.h>
 #include <asm/intel-family.h>
 #include <asm/msr.h>
+#include <asm/tsc.h>
 
 #include "intel_pmc_core.h"
 
@@ -738,7 +739,9 @@ static int pmc_core_pkgc_show(struct seq_file *s, void *unused)
 		if (rdmsrl_safe(map[index].bit_mask, &pcstate_count))
 			continue;
 
-		seq_printf(s, "%-8s : 0x%llx\n", map[index].name,
+		pcstate_count *= 1000;
+		do_div(pcstate_count, tsc_khz);
+		seq_printf(s, "%-8s : %llu\n", map[index].name,
 			   pcstate_count);
 	}
 
-- 
2.20.1