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authorWang Nan <wangnan0@huawei.com>2016-03-28 06:41:29 +0000
committerIngo Molnar <mingo@kernel.org>2016-03-31 10:30:45 +0200
commit86e7972f690c1017fd086cdfe53d8524e68c661c (patch)
tree81de100c02a7436701f2780f907039f4c16b8275 /kernel/events/internal.h
parent0a74c5b3d20d2a8693848b6ae4f1a97624f5b781 (diff)
perf/ring_buffer: Introduce new ioctl options to pause and resume the ring-buffer
Add new ioctl() to pause/resume ring-buffer output. In some situations we want to read from the ring-buffer only when we ensure nothing can write to the ring-buffer during reading. Without this patch we have to turn off all events attached to this ring-buffer to achieve this. This patch is a prerequisite to enable overwrite support for the perf ring-buffer support. Following commits will introduce new methods support reading from overwrite ring buffer. Before reading, caller must ensure the ring buffer is frozen, or the reading is unreliable. Signed-off-by: Wang Nan <wangnan0@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <pi3orama@163.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: Zefan Li <lizefan@huawei.com> Link: http://lkml.kernel.org/r/1459147292-239310-2-git-send-email-wangnan0@huawei.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/internal.h')
-rw-r--r--kernel/events/internal.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 2b229fdcfc09..2d67327d9ad9 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -17,6 +17,7 @@ struct ring_buffer {
#endif
int nr_pages; /* nr of data pages */
int overwrite; /* can overwrite itself */
+ int paused; /* can write into ring buffer */
atomic_t poll; /* POLL_ for wakeups */
@@ -64,6 +65,14 @@ static inline void rb_free_rcu(struct rcu_head *rcu_head)
rb_free(rb);
}
+static inline void rb_toggle_paused(struct ring_buffer *rb, bool pause)
+{
+ if (!pause && rb->nr_pages)
+ rb->paused = 0;
+ else
+ rb->paused = 1;
+}
+
extern struct ring_buffer *
rb_alloc(int nr_pages, long watermark, int cpu, int flags);
extern void perf_event_wakeup(struct perf_event *event);