Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967708Ab2ERVTM (ORCPT ); Fri, 18 May 2012 17:19:12 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:19964 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933132Ab2ERVTK (ORCPT ); Fri, 18 May 2012 17:19:10 -0400 X-Authority-Analysis: v=2.0 cv=ae7jbGUt c=1 sm=0 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=XQbtiDEiEegA:10 a=uChq6B4iKcYA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=meVymXHHAAAA:8 a=6h1IcWuprMDIdrxlFqcA:9 a=RGh4pXfeqi6pz_Ys_OgA:7 a=PUjeQqilurYA:10 a=jeBq3FmKZ4MA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Message-ID: <1337375946.7562.11.camel@gandalf.stny.rr.com> Subject: Re: [PATCH] power, trace: add tracing for device_resume From: Steven Rostedt To: Sameer Nanda Cc: Greg KH , rob@landley.net, len.brown@intel.com, pavel@ucw.cz, rjw@sisk.pl, fweisbec@gmail.com, mingo@redhat.com, jkosina@suse.cz, standby24x7@gmail.com, jj@chaosbits.net, paulmck@linux.vnet.ibm.com, josh@joshtriplett.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Date: Fri, 18 May 2012 17:19:06 -0400 In-Reply-To: References: <1337365643-29261-1-git-send-email-snanda@chromium.org> <20120518183756.GA3216@kroah.com> <1337368492.7562.8.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.2.2-1 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1931 Lines: 45 On Fri, 2012-05-18 at 13:58 -0700, Sameer Nanda wrote: > On Fri, May 18, 2012 at 12:14 PM, Steven Rostedt wrote: > > On Fri, 2012-05-18 at 11:57 -0700, Sameer Nanda wrote: > > > >> AFAICT, they are used for something completely different -- help solve > >> suspend/resume issues by saving a hash in the RTC of the last device > >> that suspended/resumed. They don't use the perf tracing mechanism at > >> all. > >> > > > > Also note that all tracepoints have timestamps attached to them. You do > > not need to add deltas. Do that in the userspace tools that read the > > timestamps and events. This way you can have one DECLARE_EVENT_CLASS and > > three DEFINE_EVENTs. This will save space. > > Agreed on the space savings. However, with the time_delta in the > trace message itself, a one line shell script [1] that sorts on the > time_delta field is sufficient to quickly spot the devices that take a > long time to resume. Without the time_delta field, the user tool is > more complex since it needs to first match up the device_resume_in, > device_resume_waited and device_resume_out traces and then calculate > time deltas. > > Seems like a worthwhile trade-off to me but I can take out the > time_delta if the general consensus is otherwise. Just note that every TRACE_EVENT() adds around 5k or more code. Every DEFINE_EVENT adds just about 300 bytes. > [1]: here's an example script I use for sorting the device resume times: > cat /sys/kernel/debug/tracing/trace | grep device_resume_out | awk > 'BEGIN { FS = "time_delta=" } ; { print $2 $0 }' | sort -n > Question is, how often is this done? And that 5k is permanent for all users. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/