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Message-ID: <ff22bcc8-98a2-4975-91e8-29740e6dac45@linux.intel.com> Date: Fri, 6 Sep 2024 11:26:36 -0400 From: "Liang, Kan" <kan.liang@...ux.intel.com> To: Peter Zijlstra <peterz@...radead.org> Cc: mingo@...hat.com, acme@...nel.org, namhyung@...nel.org, irogers@...gle.com, linux-kernel@...r.kernel.org Subject: Re: [PATCH 2/7] perf: Add PERF_EV_CAP_READ_SCOPE On 2024-09-06 11:11 a.m., Peter Zijlstra wrote: > On Fri, Aug 02, 2024 at 08:16:38AM -0700, kan.liang@...ux.intel.com wrote: >> From: Kan Liang <kan.liang@...ux.intel.com> >> >> Usually, an event can be read from any CPU of the scope. It doesn't need >> to be read from the advertised CPU. >> >> Add a new event cap, PERF_EV_CAP_READ_SCOPE. An event of a PMU with >> scope can be read from any active CPU in the scope. >> >> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com> >> --- >> include/linux/perf_event.h | 3 +++ >> kernel/events/core.c | 14 +++++++++++--- >> 2 files changed, 14 insertions(+), 3 deletions(-) >> >> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h >> index 1102d5c2be70..1206bc86eb4f 100644 >> --- a/include/linux/perf_event.h >> +++ b/include/linux/perf_event.h >> @@ -633,10 +633,13 @@ typedef void (*perf_overflow_handler_t)(struct perf_event *, >> * PERF_EV_CAP_SIBLING: An event with this flag must be a group sibling and >> * cannot be a group leader. If an event with this flag is detached from the >> * group it is scheduled out and moved into an unrecoverable ERROR state. >> + * PERF_EV_CAP_READ_SCOPE: A CPU event that can be read from any CPU of the >> + * PMU scope where it is active. >> */ >> #define PERF_EV_CAP_SOFTWARE BIT(0) >> #define PERF_EV_CAP_READ_ACTIVE_PKG BIT(1) >> #define PERF_EV_CAP_SIBLING BIT(2) >> +#define PERF_EV_CAP_READ_SCOPE BIT(3) >> >> #define SWEVENT_HLIST_BITS 8 >> #define SWEVENT_HLIST_SIZE (1 << SWEVENT_HLIST_BITS) >> diff --git a/kernel/events/core.c b/kernel/events/core.c >> index 5e1877c4cb4c..c55294f34575 100644 >> --- a/kernel/events/core.c >> +++ b/kernel/events/core.c >> @@ -4463,16 +4463,24 @@ struct perf_read_data { >> int ret; >> }; >> >> +static inline const struct cpumask *perf_scope_cpu_topology_cpumask(unsigned int scope, int cpu); >> + >> static int __perf_event_read_cpu(struct perf_event *event, int event_cpu) >> { >> + int local_cpu = smp_processor_id(); >> u16 local_pkg, event_pkg; >> >> if ((unsigned)event_cpu >= nr_cpu_ids) >> return event_cpu; >> >> - if (event->group_caps & PERF_EV_CAP_READ_ACTIVE_PKG) { >> - int local_cpu = smp_processor_id(); >> + if (event->group_caps & PERF_EV_CAP_READ_SCOPE) { >> + const struct cpumask *cpumask = perf_scope_cpu_topology_cpumask(event->pmu->scope, event_cpu); >> + >> + if (cpumask && cpumask_test_cpu(local_cpu, cpumask)) >> + return local_cpu; >> + } >> >> + if (event->group_caps & PERF_EV_CAP_READ_ACTIVE_PKG) { > > I'm guessing the goal is to eventually remove this one, right? Yes, after I have the uncore cleaned up. It should be able to remove the PERF_EV_CAP_READ_ACTIVE_PKG. Thanks, Kan >
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