Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757267AbcDEEyT (ORCPT ); Tue, 5 Apr 2016 00:54:19 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:1571 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754729AbcDEEw6 (ORCPT ); Tue, 5 Apr 2016 00:52:58 -0400 From: Alexei Starovoitov To: Steven Rostedt CC: Peter Zijlstra , "David S . Miller" , Ingo Molnar , Daniel Borkmann , Arnaldo Carvalho de Melo , Wang Nan , Josef Bacik , Brendan Gregg , , , Subject: [PATCH net-next 1/8] perf: optimize perf_fetch_caller_regs Date: Mon, 4 Apr 2016 21:52:47 -0700 Message-ID: <1459831974-2891931-2-git-send-email-ast@fb.com> X-Mailer: git-send-email 2.8.0 In-Reply-To: <1459831974-2891931-1-git-send-email-ast@fb.com> References: <1459831974-2891931-1-git-send-email-ast@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-04-05_05:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1609 Lines: 40 avoid memset in perf_fetch_caller_regs, since it's the critical path of all tracepoints. It's called from perf_sw_event_sched, perf_event_task_sched_in and all of perf_trace_##call with this_cpu_ptr(&__perf_regs[..]) which are zero initialized by perpcu_alloc and subsequent call to perf_arch_fetch_caller_regs initializes the same fields on all archs, so we can safely drop memset from all of the above cases and move it into perf_ftrace_function_call that calls it with stack allocated pt_regs. Signed-off-by: Alexei Starovoitov --- include/linux/perf_event.h | 2 -- kernel/trace/trace_event_perf.c | 1 + 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index f291275ffd71..e89f7199c223 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -882,8 +882,6 @@ static inline void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned lo */ static inline void perf_fetch_caller_regs(struct pt_regs *regs) { - memset(regs, 0, sizeof(*regs)); - perf_arch_fetch_caller_regs(regs, CALLER_ADDR0); } diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 00df25fd86ef..7a68afca8249 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -316,6 +316,7 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); + memset(®s, 0, sizeof(regs)); perf_fetch_caller_regs(®s); entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx); -- 2.8.0