From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760129Ab3HOTuV (ORCPT ); Thu, 15 Aug 2013 15:50:21 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59200 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759780Ab3HOTts (ORCPT ); Thu, 15 Aug 2013 15:49:48 -0400 Date: Thu, 15 Aug 2013 12:49:07 -0700 From: tip-bot for Oleg Nesterov Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, rostedt@goodmis.org, dsahern@gmail.com, tglx@linutronix.de, oleg@redhat.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, rostedt@goodmis.org, dsahern@gmail.com, tglx@linutronix.de, oleg@redhat.com In-Reply-To: <20130806160847.GA2746@redhat.com> References: <20130806160847.GA2746@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible Git-Commit-ID: d027e6a9c83440bf1ca9e5503539d58d8e0914f1 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Thu, 15 Aug 2013 12:49:13 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: d027e6a9c83440bf1ca9e5503539d58d8e0914f1 Gitweb: http://git.kernel.org/tip/d027e6a9c83440bf1ca9e5503539d58d8e0914f1 Author: Oleg Nesterov AuthorDate: Tue, 6 Aug 2013 18:08:47 +0200 Committer: Steven Rostedt CommitDate: Tue, 13 Aug 2013 21:06:30 -0400 tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible perf_trace_buf_prepare() + perf_trace_buf_submit(task => NULL) make no sense if hlist_empty(head). Change perf_trace_##call() to check ->perf_events beforehand and do nothing if it is empty. This removes the overhead for tasks without events associated with them. For example, "perf record -e sched:sched_switch -p1" attaches the counter(s) to the single task, but every task in system will do perf_trace_buf_prepare/submit() just to realize that it was not attached to this event. However, we can only do this if __task == NULL, so we also add the __builtin_constant_p(__task) check. With this patch "perf bench sched pipe" shows approximately 4% improvement when "perf record -p1" runs in parallel, many thanks to Steven for the testing. Link: http://lkml.kernel.org/r/20130806160847.GA2746@redhat.com Tested-by: David Ahern Acked-by: Peter Zijlstra Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt --- include/trace/ftrace.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index 4163d93..5c7ab17 100644 --- a/include/trace/ftrace.h +++ b/include/trace/ftrace.h @@ -667,6 +667,12 @@ perf_trace_##call(void *__data, proto) \ int rctx; \ \ __data_size = ftrace_get_offsets_##call(&__data_offsets, args); \ + \ + head = this_cpu_ptr(event_call->perf_events); \ + if (__builtin_constant_p(!__task) && !__task && \ + hlist_empty(head)) \ + return; \ + \ __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\ sizeof(u64)); \ __entry_size -= sizeof(u32); \ @@ -681,7 +687,6 @@ perf_trace_##call(void *__data, proto) \ \ { assign; } \ \ - head = this_cpu_ptr(event_call->perf_events); \ perf_trace_buf_submit(entry, __entry_size, rctx, __addr, \ __count, &__regs, head, __task); \ }