LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Tom Zanussi <zanussi@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>,
	Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jonathan Corbet <corbet@lwn.net>
Subject: Re: [PATCH v2] Documentation/trace: Add clarification how histogram onmatch works
Date: Wed, 08 May 2019 08:15:26 -0500	[thread overview]
Message-ID: <1557321326.2167.5.camel@kernel.org> (raw)
In-Reply-To: <20190507201157.2673f2de@gandalf.local.home>

Hi Steve,

On Tue, 2019-05-07 at 20:11 -0400, Steven Rostedt wrote:
> Tom,
> 
> Can you review this patch.
> 

Sure.

> Jon,
> 
> After Tom gives his review, can you take this in your tree?
> 
> Thanks!
> 
> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> 

Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>

Thanks,

Tom

> -- Steve
> 
> 
> On Tue,  7 May 2019 17:49:46 +0300
> Tzvetomir Stoyanov <tstoyanov@vmware.com> 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 <tstoyanov@vmware.com>
> > ---
> >  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/tr
> > igger
> >  
> >      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
> > ,\
> 
> 

  reply	other threads:[~2019-05-08 13:15 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-07 14:49 Tzvetomir Stoyanov
2019-05-08  0:11 ` Steven Rostedt
2019-05-08 13:15   ` Tom Zanussi [this message]
2019-05-08 16:18     ` Steven Rostedt
2019-05-08 16:22       ` Jonathan Corbet

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1557321326.2167.5.camel@kernel.org \
    --to=zanussi@kernel.org \
    --cc=corbet@lwn.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-trace-devel@vger.kernel.org \
    --cc=rostedt@goodmis.org \
    --cc=tstoyanov@vmware.com \
    --subject='Re: [PATCH v2] Documentation/trace: Add clarification how histogram onmatch works' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).