From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85226C004C9 for ; Wed, 8 May 2019 00:12:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5EF6B20675 for ; Wed, 8 May 2019 00:12:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726348AbfEHAMB (ORCPT ); Tue, 7 May 2019 20:12:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:44584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726276AbfEHAMA (ORCPT ); Tue, 7 May 2019 20:12:00 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8F4F720C01; Wed, 8 May 2019 00:11:59 +0000 (UTC) Date: Tue, 7 May 2019 20:11:57 -0400 From: Steven Rostedt To: Tzvetomir Stoyanov Cc: linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Zanussi , Jonathan Corbet Subject: Re: [PATCH v2] Documentation/trace: Add clarification how histogram onmatch works Message-ID: <20190507201157.2673f2de@gandalf.local.home> In-Reply-To: <20190507144946.7998-1-tstoyanov@vmware.com> References: <20190507144946.7998-1-tstoyanov@vmware.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Tom, Can you review this patch. Jon, After Tom gives his review, can you take this in your tree? Thanks! Reviewed-by: Steven Rostedt (VMware) -- Steve On Tue, 7 May 2019 17:49:46 +0300 Tzvetomir Stoyanov wrote: > The current trace documentation, the section describing histogram's "onmatch" > is not straightforward enough about how this action is applied. It is not > clear what criteria are used to "match" both events. A short note is added, > describing what exactly is compared in order to match the events. > > Signed-off-by: Tzvetomir Stoyanov > --- > Documentation/trace/histogram.txt | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt > index 7ffea6aa22e3..d97f0530a731 100644 > --- a/Documentation/trace/histogram.txt > +++ b/Documentation/trace/histogram.txt > @@ -1863,7 +1863,10 @@ hist trigger specification. > > The 'matching.event' specification is simply the fully qualified > event name of the event that matches the target event for the > - onmatch() functionality, in the form 'system.event_name'. > + onmatch() functionality, in the form 'system.event_name'. Histogram > + keys of both events are compared to find if events match. In the case > + multiple histogram keys are used, both events must have the same > + number of keys, and the keys must match in the same order. > > Finally, the number and type of variables/fields in the 'param > list' must match the number and types of the fields in the > @@ -1920,9 +1923,10 @@ hist trigger specification. > /sys/kernel/debug/tracing/events/sched/sched_waking/trigger > > Then, when the corresponding thread is actually scheduled onto the > - CPU by a sched_switch event, calculate the latency and use that > - along with another variable and an event field to generate a > - wakeup_latency synthetic event: > + CPU by a sched_switch event (where the sched_waking key "saved_pid" > + matches the sched_switch key "next_pid"), calculate the latency and > + use that along with another variable and an event field to generate > + a wakeup_latency synthetic event: > > # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:\ > onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,\