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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>
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1 changed files with 8 additions and 5 deletions
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@ -106,7 +106,6 @@ int perf_output_begin(struct perf_output_handle *handle,
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struct ring_buffer *rb;
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struct ring_buffer *rb;
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unsigned long tail, offset, head;
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unsigned long tail, offset, head;
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int have_lost;
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int have_lost;
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struct perf_sample_data sample_data;
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struct {
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struct {
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struct perf_event_header header;
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struct perf_event_header header;
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u64 id;
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u64 id;
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@ -132,10 +131,9 @@ int perf_output_begin(struct perf_output_handle *handle,
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have_lost = local_read(&rb->lost);
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have_lost = local_read(&rb->lost);
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if (unlikely(have_lost)) {
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if (unlikely(have_lost)) {
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lost_event.header.size = sizeof(lost_event);
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size += sizeof(lost_event);
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perf_event_header__init_id(&lost_event.header, &sample_data,
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if (event->attr.sample_id_all)
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event);
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size += event->id_header_size;
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size += lost_event.header.size;
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}
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}
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perf_output_get_handle(handle);
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perf_output_get_handle(handle);
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@ -169,11 +167,16 @@ int perf_output_begin(struct perf_output_handle *handle,
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handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;
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handle->size = (PAGE_SIZE << page_order(rb)) - handle->size;
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if (unlikely(have_lost)) {
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if (unlikely(have_lost)) {
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struct perf_sample_data sample_data;
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lost_event.header.size = sizeof(lost_event);
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lost_event.header.type = PERF_RECORD_LOST;
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lost_event.header.type = PERF_RECORD_LOST;
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lost_event.header.misc = 0;
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lost_event.header.misc = 0;
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lost_event.id = event->id;
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lost_event.id = event->id;
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lost_event.lost = local_xchg(&rb->lost, 0);
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lost_event.lost = local_xchg(&rb->lost, 0);
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perf_event_header__init_id(&lost_event.header,
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&sample_data, event);
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perf_output_put(handle, lost_event);
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perf_output_put(handle, lost_event);
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perf_event__output_id_sample(event, handle, &sample_data);
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perf_event__output_id_sample(event, handle, &sample_data);
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}
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}
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