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Subject[PATCH v3] platform/x86: intel_pmc_core: transform Pkg C-state residency from TSC ticks into microseconds
Date
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@intel.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
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