linux-kernel - [RESEND PATCH 1/2] perf/x86/cstate: Allow reading the package statistics from local CPU

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Message-Id: <20230912124432.3616761-2-tero.kristo@linux.intel.com>
Date:   Tue, 12 Sep 2023 15:44:31 +0300
From:   Tero Kristo <tero.kristo@...ux.intel.com>
To:     x86@...nel.org, tglx@...utronix.de, bp@...en8.de,
        dave.hansen@...ux.intel.com
Cc:     irogers@...gle.com, mark.rutland@....com,
        linux-perf-users@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org, acme@...nel.org,
        peterz@...radead.org, alexander.shishkin@...ux.intel.com,
        adrian.hunter@...el.com, namhyung@...nel.org, jolsa@...nel.org,
        Kan Liang <kan.liang@...el.com>
Subject: [RESEND PATCH 1/2] perf/x86/cstate: Allow reading the package statistics from local CPU

The MSR registers for reading the package residency counters are
available on every CPU of the package. To avoid doing unnecessary SMP
calls to read the values for these from the various CPUs inside a
package, allow reading them from any CPU of the package.

Signed-off-by: Tero Kristo <tero.kristo@...ux.intel.com>
Suggested-by: Kan Liang <kan.liang@...el.com>
---
 arch/x86/events/intel/cstate.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/events/intel/cstate.c b/arch/x86/events/intel/cstate.c
index 96fffb2d521d..cbeb6d2bf5b4 100644
--- a/arch/x86/events/intel/cstate.c
+++ b/arch/x86/events/intel/cstate.c
@@ -336,6 +336,9 @@ static int cstate_pmu_event_init(struct perf_event *event)
 		cfg = array_index_nospec((unsigned long)cfg, PERF_CSTATE_PKG_EVENT_MAX);
 		if (!(pkg_msr_mask & (1 << cfg)))
 			return -EINVAL;
+
+		event->event_caps |= PERF_EV_CAP_READ_ACTIVE_PKG;
+
 		event->hw.event_base = pkg_msr[cfg].msr;
 		cpu = cpumask_any_and(&cstate_pkg_cpu_mask,
 				      topology_die_cpumask(event->cpu));
-- 
2.40.1