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Message-ID: <ZqQ9NnEF8oDGhatU@ghost>
Date: Fri, 26 Jul 2024 17:20:06 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Atish Patra <atishp@...osinc.com>
Cc: linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT
On Wed, Jul 24, 2024 at 03:43:25PM -0700, Charlie Jenkins wrote:
> PERF_EVENT_IOC_REFRESH immediately enables after incrementing
> event_limit. Provide a new ioctl flag that allows programs to increment
> event_limit without enabling the event. A usecase for this is to set an
> event_limit in combination with enable_on_exec.
>
> Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
> ---
> include/linux/perf_event.h | 4 ++--
> include/uapi/linux/perf_event.h | 1 +
> kernel/events/core.c | 17 +++++++++++------
> tools/include/uapi/linux/perf_event.h | 1 +
> 4 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index a5304ae8c654..40025a5eb98a 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -1103,7 +1103,7 @@ extern int perf_event_task_enable(void);
>
> extern void perf_pmu_resched(struct pmu *pmu);
>
> -extern int perf_event_refresh(struct perf_event *event, int refresh);
> +extern int perf_event_refresh(struct perf_event *event, int refresh, bool enable);
> extern void perf_event_update_userpage(struct perf_event *event);
> extern int perf_event_release_kernel(struct perf_event *event);
> extern struct perf_event *
> @@ -1770,7 +1770,7 @@ static inline int perf_event_read_local(struct perf_event *event, u64 *value,
> static inline void perf_event_print_debug(void) { }
> static inline int perf_event_task_disable(void) { return -EINVAL; }
> static inline int perf_event_task_enable(void) { return -EINVAL; }
> -static inline int perf_event_refresh(struct perf_event *event, int refresh)
> +static inline int perf_event_refresh(struct perf_event *event, int refresh, bool enable)
> {
> return -EINVAL;
> }
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index 3a64499b0f5d..992f51effb27 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -560,6 +560,7 @@ struct perf_event_query_bpf {
> #define PERF_EVENT_IOC_PAUSE_OUTPUT _IOW('$', 9, __u32)
> #define PERF_EVENT_IOC_QUERY_BPF _IOWR('$', 10, struct perf_event_query_bpf *)
> #define PERF_EVENT_IOC_MODIFY_ATTRIBUTES _IOW('$', 11, struct perf_event_attr *)
> +#define PERF_EVENT_IOC_INC_EVENT_LIMIT _IO ('$', 12)
>
> enum perf_event_ioc_flags {
> PERF_IOC_FLAG_GROUP = 1U << 0,
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 8f908f077935..b9d009733ace 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -3142,7 +3142,7 @@ void perf_event_addr_filters_sync(struct perf_event *event)
> }
> EXPORT_SYMBOL_GPL(perf_event_addr_filters_sync);
>
> -static int _perf_event_refresh(struct perf_event *event, int refresh)
> +static int _perf_event_refresh(struct perf_event *event, int refresh, bool enable)
> {
> /*
> * not supported on inherited events
> @@ -3151,7 +3151,8 @@ static int _perf_event_refresh(struct perf_event *event, int refresh)
> return -EINVAL;
>
> atomic_add(refresh, &event->event_limit);
> - _perf_event_enable(event);
> + if (enable)
> + _perf_event_enable(event);
>
> return 0;
> }
> @@ -3159,13 +3160,13 @@ static int _perf_event_refresh(struct perf_event *event, int refresh)
> /*
> * See perf_event_disable()
> */
> -int perf_event_refresh(struct perf_event *event, int refresh)
> +int perf_event_refresh(struct perf_event *event, int refresh, bool enable)
> {
> struct perf_event_context *ctx;
> int ret;
>
> ctx = perf_event_ctx_lock(event);
> - ret = _perf_event_refresh(event, refresh);
> + ret = _perf_event_refresh(event, refresh, enable);
> perf_event_ctx_unlock(event, ctx);
>
> return ret;
> @@ -5920,7 +5921,7 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
> break;
>
> case PERF_EVENT_IOC_REFRESH:
> - return _perf_event_refresh(event, arg);
> + return _perf_event_refresh(event, arg, true);
>
> case PERF_EVENT_IOC_PERIOD:
> {
> @@ -6006,6 +6007,10 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
>
> return perf_event_modify_attr(event, &new_attr);
> }
> +
> + case PERF_EVENT_IOC_INC_EVENT_LIMIT:
> + return _perf_event_refresh(event, arg, false);
> +
> default:
> return -ENOTTY;
> }
> @@ -6721,7 +6726,7 @@ void perf_event_wakeup(struct perf_event *event)
> ring_buffer_wakeup(event);
>
> if (event->pending_kill) {
> - kill_fasync(perf_event_fasync(event), SIGIO, event->pending_kill);
> + kill_fasync(perf_event_fasync(event), SIGTRAP, event->pending_kill);
This was a debug change that wasn't supposed to make it into this patch.
In the next version I will remove this.
- Charlie
> event->pending_kill = 0;
> }
> }
> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
> index 3a64499b0f5d..992f51effb27 100644
> --- a/tools/include/uapi/linux/perf_event.h
> +++ b/tools/include/uapi/linux/perf_event.h
> @@ -560,6 +560,7 @@ struct perf_event_query_bpf {
> #define PERF_EVENT_IOC_PAUSE_OUTPUT _IOW('$', 9, __u32)
> #define PERF_EVENT_IOC_QUERY_BPF _IOWR('$', 10, struct perf_event_query_bpf *)
> #define PERF_EVENT_IOC_MODIFY_ATTRIBUTES _IOW('$', 11, struct perf_event_attr *)
> +#define PERF_EVENT_IOC_INC_EVENT_LIMIT _IO ('$', 12)
>
> enum perf_event_ioc_flags {
> PERF_IOC_FLAG_GROUP = 1U << 0,
>
> --
> 2.44.0
>
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