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 <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kaixu Xia <kaixu.xia@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Robert Richter <rric@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: acme@infradead.org Cc: adrian.hunter@intel.com Cc: kan.liang@intel.com Cc: markus.t.metzger@intel.com Cc: mathieu.poirier@linaro.org Link: http://lkml.kernel.org/r/1421237903-181015-10-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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2023a0d282
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1a59413124
4 changed files with 31 additions and 5 deletions
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@ -261,6 +261,7 @@ enum perf_event_read_format {
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#define PERF_ATTR_SIZE_VER3 96 /* add: sample_regs_user */
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/* add: sample_stack_user */
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#define PERF_ATTR_SIZE_VER4 104 /* add: sample_regs_intr */
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#define PERF_ATTR_SIZE_VER5 112 /* add: aux_watermark */
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/*
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* Hardware event_id to monitor via a performance monitoring event:
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@ -366,6 +367,12 @@ struct perf_event_attr {
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* See asm/perf_regs.h for details.
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*/
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__u64 sample_regs_intr;
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/*
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* Wakeup watermark for AUX area
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*/
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__u32 aux_watermark;
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__u32 __reserved_2; /* align to __u64 */
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};
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#define perf_flags(attr) (*(&(attr)->read_format + 1))
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@ -4677,7 +4677,8 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
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perf_event_init_userpage(event);
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perf_event_update_userpage(event);
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} else {
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ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages, flags);
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ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
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event->attr.aux_watermark, flags);
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if (!ret)
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rb->aux_mmap_locked = extra;
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}
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@ -27,6 +27,7 @@ struct ring_buffer {
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local_t lost; /* nr records lost */
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long watermark; /* wakeup watermark */
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long aux_watermark;
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/* poll crap */
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spinlock_t event_lock;
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struct list_head event_list;
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@ -38,6 +39,7 @@ struct ring_buffer {
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/* AUX area */
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local_t aux_head;
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local_t aux_nest;
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local_t aux_wakeup;
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unsigned long aux_pgoff;
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int aux_nr_pages;
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int aux_overwrite;
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@ -57,7 +59,7 @@ extern struct ring_buffer *
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rb_alloc(int nr_pages, long watermark, int cpu, int flags);
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extern void perf_event_wakeup(struct perf_event *event);
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extern int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event,
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pgoff_t pgoff, int nr_pages, int flags);
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pgoff_t pgoff, int nr_pages, long watermark, int flags);
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extern void rb_free_aux(struct ring_buffer *rb);
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extern struct ring_buffer *ring_buffer_get(struct perf_event *event);
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extern void ring_buffer_put(struct ring_buffer *rb);
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@ -296,6 +296,7 @@ void *perf_aux_output_begin(struct perf_output_handle *handle,
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*/
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if (!rb->aux_overwrite) {
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aux_tail = ACCESS_ONCE(rb->user_page->aux_tail);
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handle->wakeup = local_read(&rb->aux_wakeup) + rb->aux_watermark;
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if (aux_head - aux_tail < perf_aux_size(rb))
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handle->size = CIRC_SPACE(aux_head, aux_tail, perf_aux_size(rb));
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@ -359,9 +360,12 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
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perf_event_aux_event(handle->event, aux_head, size, flags);
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}
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rb->user_page->aux_head = local_read(&rb->aux_head);
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aux_head = rb->user_page->aux_head = local_read(&rb->aux_head);
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perf_output_wakeup(handle);
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if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) {
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perf_output_wakeup(handle);
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local_add(rb->aux_watermark, &rb->aux_wakeup);
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}
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handle->event = NULL;
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local_set(&rb->aux_nest, 0);
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@ -383,6 +387,14 @@ int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size)
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local_add(size, &rb->aux_head);
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aux_head = rb->user_page->aux_head = local_read(&rb->aux_head);
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if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) {
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perf_output_wakeup(handle);
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local_add(rb->aux_watermark, &rb->aux_wakeup);
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handle->wakeup = local_read(&rb->aux_wakeup) +
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rb->aux_watermark;
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}
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handle->head = aux_head;
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handle->size -= size;
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@ -433,7 +445,7 @@ static void rb_free_aux_page(struct ring_buffer *rb, int idx)
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}
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int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event,
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pgoff_t pgoff, int nr_pages, int flags)
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pgoff_t pgoff, int nr_pages, long watermark, int flags)
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{
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bool overwrite = !(flags & RING_BUFFER_WRITABLE);
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int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu);
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@ -497,6 +509,10 @@ int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event,
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atomic_set(&rb->aux_refcount, 1);
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rb->aux_overwrite = overwrite;
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rb->aux_watermark = watermark;
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if (!rb->aux_watermark && !rb->aux_overwrite)
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rb->aux_watermark = nr_pages << (PAGE_SHIFT - 1);
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out:
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if (!ret)
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