Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751950AbdGAHBn (ORCPT ); Sat, 1 Jul 2017 03:01:43 -0400 Received: from mail-wm0-f50.google.com ([74.125.82.50]:37697 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751563AbdGAHBl (ORCPT ); Sat, 1 Jul 2017 03:01:41 -0400 MIME-Version: 1.0 In-Reply-To: References: From: "Joel Fernandes (Google)" Date: Sat, 1 Jul 2017 00:01:39 -0700 Message-ID: Subject: Re: [PATCH 00/32] tracing: Inter-event (e.g. latency) support To: Tom Zanussi Cc: rostedt@goodmis.org, tglx@linutronix.de, mhiramat@kernel.org, namhyung@kernel.org, vedang.patel@intel.com, Linux Kernel Mailing List , linux-rt-users@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1262 Lines: 29 Hi Tom, Nice series and nice ELC talk as well. Thanks. On Mon, Jun 26, 2017 at 3:49 PM, Tom Zanussi wrote: > This patchset adds support for 'inter-event' quantities to the trace > event subsystem. The most important example of inter-event quantities > are latencies, or the time differences between two events. I tried your patches out and they are working fine for me. I will test them out more. I think for the wakeup latency in your examples, its better / more accurate to use sched_waking instead of sched_wakeup tracepoint? [1] Also, one other comment I had is, it would be nice to suppress the output of individual trace events that are part of the synthetic event into the trace buffer. Otherwise I feel the value of it is slightly diminished - because one can simply post-process the individual non-synthetic trace events themselves to get wake up latencies which the synthetic events is trying to calculate in the first place. Inorder to conserve space, if a user doesn't care about individual events, and just the synthetic events then the individual ones shouldn't be written to the trace buffer IMO. -Joel [1] commit fbd705a0c6184580d0e2fbcbd47a37b6e5822511 (sched: Introduce the 'trace_sched_waking' tracepoint)