Commit-ID: 1a5941312414c71dece6717da9a0fa1303127afa Gitweb: http://git.kernel.org/tip/1a5941312414c71dece6717da9a0fa1303127afa Author: Alexander Shishkin <[email protected]> AuthorDate: Wed, 14 Jan 2015 14:18:18 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 2 Apr 2015 17:14:16 +0200
perf: Add wakeup watermark control to the AUX area When AUX area gets a certain amount of new data, we want to wake up userspace to collect it. This adds a new control to specify how much data will cause a wakeup. This is then passed down to pmu drivers via output handle's "wakeup" field, so that the driver can find the nearest point where it can generate an interrupt. We repurpose __reserved_2 in the event attribute for this, even though it was never checked to be zero before, aux_watermark will only matter for new AUX-aware code, so the old code should still be fine. Signed-off-by: Alexander Shishkin <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Kaixu Xia <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Robert Richter <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/1421237903-181015-10-git-send-email-alexander.shish...@linux.intel.com Signed-off-by: Ingo Molnar <[email protected]> --- include/uapi/linux/perf_event.h | 7 +++++++ kernel/events/core.c | 3 ++- kernel/events/internal.h | 4 +++- kernel/events/ring_buffer.c | 22 +++++++++++++++++++--- 4 files changed, 31 insertions(+), 5 deletions(-) diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 29ef2f7..84819546 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -261,6 +261,7 @@ enum perf_event_read_format { #define PERF_ATTR_SIZE_VER3 96 /* add: sample_regs_user */ /* add: sample_stack_user */ #define PERF_ATTR_SIZE_VER4 104 /* add: sample_regs_intr */ +#define PERF_ATTR_SIZE_VER5 112 /* add: aux_watermark */ /* * Hardware event_id to monitor via a performance monitoring event: @@ -366,6 +367,12 @@ struct perf_event_attr { * See asm/perf_regs.h for details. */ __u64 sample_regs_intr; + + /* + * Wakeup watermark for AUX area + */ + __u32 aux_watermark; + __u32 __reserved_2; /* align to __u64 */ }; #define perf_flags(attr) (*(&(attr)->read_format + 1)) diff --git a/kernel/events/core.c b/kernel/events/core.c index 81e8d14..31f6b50 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4677,7 +4677,8 @@ accounting: perf_event_init_userpage(event); perf_event_update_userpage(event); } else { - ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages, flags); + ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages, + event->attr.aux_watermark, flags); if (!ret) rb->aux_mmap_locked = extra; } diff --git a/kernel/events/internal.h b/kernel/events/internal.h index ffd51d9..9f6ce9b 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -27,6 +27,7 @@ struct ring_buffer { local_t lost; /* nr records lost */ long watermark; /* wakeup watermark */ + long aux_watermark; /* poll crap */ spinlock_t event_lock; struct list_head event_list; @@ -38,6 +39,7 @@ struct ring_buffer { /* AUX area */ local_t aux_head; local_t aux_nest; + local_t aux_wakeup; unsigned long aux_pgoff; int aux_nr_pages; int aux_overwrite; @@ -57,7 +59,7 @@ extern struct ring_buffer * rb_alloc(int nr_pages, long watermark, int cpu, int flags); extern void perf_event_wakeup(struct perf_event *event); extern int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, - pgoff_t pgoff, int nr_pages, int flags); + pgoff_t pgoff, int nr_pages, long watermark, int flags); 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); diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 67b3283..232f00f 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -296,6 +296,7 @@ void *perf_aux_output_begin(struct perf_output_handle *handle, */ if (!rb->aux_overwrite) { aux_tail = ACCESS_ONCE(rb->user_page->aux_tail); + handle->wakeup = local_read(&rb->aux_wakeup) + rb->aux_watermark; if (aux_head - aux_tail < perf_aux_size(rb)) handle->size = CIRC_SPACE(aux_head, aux_tail, perf_aux_size(rb)); @@ -359,9 +360,12 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size, perf_event_aux_event(handle->event, aux_head, size, flags); } - rb->user_page->aux_head = local_read(&rb->aux_head); + aux_head = rb->user_page->aux_head = local_read(&rb->aux_head); - perf_output_wakeup(handle); + if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) { + perf_output_wakeup(handle); + local_add(rb->aux_watermark, &rb->aux_wakeup); + } handle->event = NULL; local_set(&rb->aux_nest, 0); @@ -383,6 +387,14 @@ int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size) local_add(size, &rb->aux_head); + aux_head = rb->user_page->aux_head = local_read(&rb->aux_head); + if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) { + perf_output_wakeup(handle); + local_add(rb->aux_watermark, &rb->aux_wakeup); + handle->wakeup = local_read(&rb->aux_wakeup) + + rb->aux_watermark; + } + handle->head = aux_head; handle->size -= size; @@ -433,7 +445,7 @@ static void rb_free_aux_page(struct ring_buffer *rb, int idx) } int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, - pgoff_t pgoff, int nr_pages, int flags) + pgoff_t pgoff, int nr_pages, long watermark, int flags) { bool overwrite = !(flags & RING_BUFFER_WRITABLE); int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu); @@ -497,6 +509,10 @@ int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, atomic_set(&rb->aux_refcount, 1); rb->aux_overwrite = overwrite; + rb->aux_watermark = watermark; + + if (!rb->aux_watermark && !rb->aux_overwrite) + rb->aux_watermark = nr_pages << (PAGE_SHIFT - 1); out: if (!ret) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
