Commit-ID: d20a973f46ed83e0d7d24f6c512064133038e193 Gitweb: http://git.kernel.org/tip/d20a973f46ed83e0d7d24f6c512064133038e193 Author: Peter Zijlstra <[email protected]> AuthorDate: Thu, 31 Oct 2013 17:29:29 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 6 Nov 2013 12:34:21 +0100
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 <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Mathieu Desnoyers <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Michael Neuling <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Cc: [email protected] Cc: Vince Weaver <[email protected]> Cc: Victor Kaplansky <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Anton Blanchard <[email protected]> Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/events/ring_buffer.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 6ed16ec..e4d70f3 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); } -- 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/
