From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christopher Covington Subject: Re: [PATCH 0/2] perf: User/kernel time correlation and event generation Date: Thu, 18 Sep 2014 11:02:35 -0400 Message-ID: <541AF40B.7070604@codeaurora.org> References: <1411050873-9310-1-git-send-email-pawel.moll@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1411050873-9310-1-git-send-email-pawel.moll-5wv7dgnIgG8@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Pawel Moll Cc: Richard Cochran , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Paul Mackerras , Arnaldo Carvalho de Melo , John Stultz , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michael Kerrisk List-Id: linux-api@vger.kernel.org Hi Pawel, On 09/18/2014 10:34 AM, Pawel Moll wrote: > Greetings, > > This is a second spin of the short series posted last week: > > http://www.spinics.net/lists/kernel/msg1824419.html > > The first patch adds an additional timestamp field in the perf > sample data, which can be requested for any perf event along > with normal PERF_SAMPLE_TIME. Events with both values appearing > periodically in the perf data allow user code to translate > raw monotonic time (obtained via POSIX clock API) to sched_clock > domain. Although any perf event can be used, the natural choice > would be a sched_switch trace event (for processes with root > permissions) or a hrtimer-based PERF_COUNT_SW_CPU_CLOCK. > > It didn't attract any comments previously, so is just re-posted > without any changes. > > The second patch, functionally orthogonal but complementing > the first one, builds on the ftrace "trace_maker" idea. It adds > a ioctl that can be used to inject a userspace-generated data > into the perf buffer. It provides base for printf-like > functionality in perf world. If used with the previous patch, > it can be also used to provide synchronisation points for sched > vs. raw monotonic time stamps correlation. > > First version of the patch was taking a zero-terminated string > as an argument. Now it is taking a custom structure with "type" > and "size" integer fields followed by data. Type value "0" > is defined as a zero-terminated string (although size, including > the NULL character, must still be provided), but meaning of data > for other types is of no interest for the kernel. The intention > is to host a list of "well known" types (with reference parsers > for them) in the user perf tool code. Would it be possible for you to also update the corresponding man pages? https://www.kernel.org/doc/man-pages/ Thanks, Christopher -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation.