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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2010-05-20 16:21:55 +0200
committerIngo Molnar <mingo@elte.hu>2010-05-21 11:37:58 +0200
commitadb8e118f288dc4c569ac9a89010b81a4745fbf0 (patch)
tree40f2bbbe7c59fb4b4a44120fa9cc79822b68e545 /kernel/perf_event.c
parent0e2e63dd608bf5844ffae7bf7d860de18a62724c (diff)
perf: Fix wakeup storm for RO mmap()s
RO mmap()s don't update the tail pointer, so comparing against it for determining the written data size doesn't really do any good. Keep track of when we last did a wakeup, and compare against that. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <20100521090710.684479310@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
-rw-r--r--kernel/perf_event.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 7a932526946f..1531e0b409a5 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3056,8 +3056,8 @@ int perf_output_begin(struct perf_output_handle *handle,
handle->offset = offset;
handle->head = head;
- if (head - tail > data->watermark)
- local_inc(&data->wakeup);
+ if (head - local_read(&data->wakeup) > data->watermark)
+ local_add(data->watermark, &data->wakeup);
if (have_lost) {
lost_event.header.type = PERF_RECORD_LOST;