Messages in this thread Patch in this message | | | From | "Naveen N. Rao" <> | Subject | [PATCH v2 2/2] kernel/events: Add option to enable counting sideband events in wakeup_events | Date | Tue, 1 Aug 2017 20:14:04 +0530 |
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Many sideband events are interesting by themselves. When profiling only for sideband events, it is useful to be able to control process wakeup (wakeup_events) based on sideband events alone. Add a new option 'count_sb_events' to do the same.
IOC_REFRESH won't be supported with this, so disable that.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- include/uapi/linux/perf_event.h | 3 ++- kernel/events/core.c | 23 +++++++---------------- kernel/events/internal.h | 1 + kernel/events/ring_buffer.c | 18 ++++++++++++++++++ 4 files changed, 28 insertions(+), 17 deletions(-)
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index e5810b1d74a4..ab4dc9a02151 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -346,7 +346,8 @@ struct perf_event_attr { write_backward : 1, /* Write ring buffer from end to beginning */ namespaces : 1, /* include namespaces data */ signal_on_wakeup : 1, /* send signal on wakeup */ - __reserved_1 : 34; + count_sb_events : 1, /* wakeup_events also counts sideband events */ + __reserved_1 : 33; union { __u32 wakeup_events; /* wakeup every n events */ diff --git a/kernel/events/core.c b/kernel/events/core.c index 4fe708a4fdee..118a100108b1 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2680,11 +2680,13 @@ EXPORT_SYMBOL_GPL(perf_event_addr_filters_sync); static int _perf_event_refresh(struct perf_event *event, int refresh) { /* - * not supported on inherited events or if user has requested for - * signals on ring buffer wakeup. + * not supported on: + * - inherited events + * - if user has requested for signals on ring buffer wakeup, or + * - if counting sideband events */ if (event->attr.inherit || event->attr.signal_on_wakeup || - !is_sampling_event(event)) + event->attr.count_sb_events || !is_sampling_event(event)) return -EINVAL; atomic_add(refresh, &event->event_limit); @@ -5974,19 +5976,8 @@ void perf_output_sample(struct perf_output_handle *handle, } } - if (!event->attr.watermark) { - int wakeup_events = event->attr.wakeup_events; - - if (wakeup_events) { - struct ring_buffer *rb = handle->rb; - int events = local_inc_return(&rb->events); - - if (events >= wakeup_events) { - local_sub(wakeup_events, &rb->events); - local_inc(&rb->wakeup); - } - } - } + if (!event->attr.count_sb_events) + rb_handle_wakeup_events(event, handle->rb); } void perf_prepare_sample(struct perf_event_header *header, diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 486fd78eb8d5..b75137ebe9f7 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -81,6 +81,7 @@ extern int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, extern void rb_free_aux(struct ring_buffer *rb); extern struct ring_buffer *ring_buffer_get(struct perf_event *event); extern void ring_buffer_put(struct ring_buffer *rb); +extern void rb_handle_wakeup_events(struct perf_event *event, struct ring_buffer *rb); static inline bool rb_has_aux(struct ring_buffer *rb) { diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index e7a558cfcadb..a34f5c2e7ed1 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -116,6 +116,21 @@ ring_buffer_has_space(unsigned long head, unsigned long tail, return CIRC_SPACE(tail, head, data_size) >= size; } +void __always_inline +rb_handle_wakeup_events(struct perf_event *event, struct ring_buffer *rb) +{ + int wakeup_events = event->attr.wakeup_events; + + if (!event->attr.watermark && wakeup_events) { + int events = local_inc_return(&rb->events); + + if (events >= wakeup_events) { + local_sub(wakeup_events, &rb->events); + local_inc(&rb->wakeup); + } + } +} + static int __always_inline __perf_output_begin(struct perf_output_handle *handle, struct perf_event *event, unsigned int size, @@ -197,6 +212,9 @@ __perf_output_begin(struct perf_output_handle *handle, * none of the data stores below can be lifted up by the compiler. */ + if (unlikely(event->attr.count_sb_events)) + rb_handle_wakeup_events(event, rb); + if (unlikely(head - local_read(&rb->wakeup) > rb->watermark)) local_add(rb->watermark, &rb->wakeup); -- 2.13.3
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