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authorPeter Zijlstra <peterz@infradead.org>2013-10-31 20:29:29 +0400
committerIngo Molnar <mingo@kernel.org>2013-11-06 15:34:21 +0400
commitd20a973f46ed83e0d7d24f6c512064133038e193 (patch)
tree67480d93b9ed6b23cede1e861aa4daf4bf345782 /kernel/events/ring_buffer.c
parent85f59edf9684603026c64c902791748116d29478 (diff)
downloadlinux-d20a973f46ed83e0d7d24f6c512064133038e193.tar.xz
perf: Optimize perf_output_begin() -- lost_event case
Avoid touching the lost_event and sample_data cachelines twince. Its not like we end up doing less work, but it might help to keep all accesses to these cachelines in one place. Due to code shuffle, this looses 4 bytes on x86_64-defconfig. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Michael Neuling <mikey@neuling.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: james.hogan@imgtec.com Cc: Vince Weaver <vince@deater.net> Cc: Victor Kaplansky <VICTORK@il.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Anton Blanchard <anton@samba.org> Link: http://lkml.kernel.org/n/tip-zfxnc58qxj0eawdoj31hhupv@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/ring_buffer.c')
-rw-r--r--kernel/events/ring_buffer.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 6ed16ecfd0a3..e4d70f33792f 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -106,7 +106,6 @@ int perf_output_begin(struct perf_output_handle *handle,
struct ring_buffer *rb;
unsigned long tail, offset, head;
int have_lost;
- struct perf_sample_data sample_data;
struct {
struct perf_event_header header;
u64 id;
@@ -132,10 +131,9 @@ int perf_output_begin(struct perf_output_handle *handle,
have_lost = local_read(&rb->lost);
if (unlikely(have_lost)) {
- lost_event.header.size = sizeof(lost_event);
- perf_event_header__init_id(&lost_event.header, &sample_data,
- event);
- size += lost_event.header.size;
+ size += sizeof(lost_event);
+ if (event->attr.sample_id_all)
+ size += event->id_header_size;
}
perf_output_get_handle(handle);
@@ -169,11 +167,16 @@ int perf_output_begin(struct perf_output_handle *handle,
handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;
if (unlikely(have_lost)) {
+ struct perf_sample_data sample_data;
+
+ lost_event.header.size = sizeof(lost_event);
lost_event.header.type = PERF_RECORD_LOST;
lost_event.header.misc = 0;
lost_event.id = event->id;
lost_event.lost = local_xchg(&rb->lost, 0);
+ perf_event_header__init_id(&lost_event.header,
+ &sample_data, event);
perf_output_put(handle, lost_event);
perf_event__output_id_sample(event, handle, &sample_data);
}