From 8c7eb17e722a6a45c4436e5debb9336089b21d9b Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Fri, 2 Aug 2024 08:16:38 -0700 Subject: perf: Add PERF_EV_CAP_READ_SCOPE 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 --- include/linux/perf_event.h | 3 +++ kernel/events/core.c | 14 +++++++++++--- 2 files changed, 14 insertions(+), 3 deletions(-) --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -633,10 +633,13 @@ typedef void (*perf_overflow_handler_t)( * 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) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4477,16 +4477,24 @@ 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) { event_pkg = topology_physical_package_id(event_cpu); local_pkg = topology_physical_package_id(local_cpu); @@ -11824,7 +11832,7 @@ static int perf_try_init_event(struct pm if (cpu >= nr_cpu_ids) ret = -ENODEV; else - event->cpu = cpu; + event->event_caps |= PERF_EV_CAP_READ_SCOPE; } else { ret = -ENODEV; }