[tip: x86/cleanups] x86/aperfmperf: Store aperf/mperf data for cpu frequency reads

tip-bot2 for Thomas Gleixner
2022-04-27T18:43:13Z

The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID: cd8c0e142daf9de9ce594e61b75509b0af7bfb26
Gitweb: https://git.kernel.org/tip/cd8c0e142daf9de9ce594e61b75509b0af7bfb26
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Fri, 15 Apr 2022 21:20:01 +02:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 27 Apr 2022 20:22:19 +02:00

x86/aperfmperf: Store aperf/mperf data for cpu frequency reads

Now that the MSR readout is unconditional, store the results in the per CPU
data structure along with a jiffies timestamp for the CPU frequency readout
code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20220415161206.817702355@linutronix.de

---
arch/x86/kernel/cpu/aperfmperf.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
index df528a4..963c069 100644
--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -24,11 +24,17 @@
#include "cpu.h"

struct aperfmperf {
+ seqcount_t seq;
+ unsigned long last_update;
+ u64 acnt;
+ u64 mcnt;
u64 aperf;
u64 mperf;
};

-static DEFINE_PER_CPU_SHARED_ALIGNED(struct aperfmperf, cpu_samples);
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct aperfmperf, cpu_samples) = {
+ .seq = SEQCNT_ZERO(cpu_samples.seq)
+};

struct aperfmperf_sample {
unsigned int khz;
@@ -515,6 +521,12 @@ void arch_scale_freq_tick(void)
s->aperf = aperf;
s->mperf = mperf;

+ raw_write_seqcount_begin(&s->seq);
+ s->last_update = jiffies;
+ s->acnt = acnt;
+ s->mcnt = mcnt;
+ raw_write_seqcount_end(&s->seq);
+
scale_freq_tick(acnt, mcnt);
}