linux-kernel - Re: [BUG] perf top: -z option does not work

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Message-ID: <20140812122448.GA2184@redhat.com>
Date:	Tue, 12 Aug 2014 09:24:48 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Stephane Eranian <eranian@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jiri Olsa <jolsa@...hat.com>, "mingo@...e.hu" <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	David Ahern <dsahern@...il.com>
Subject: Re: [BUG] perf top: -z option does not work

Em Tue, Aug 12, 2014 at 05:09:17PM +0900, Namhyung Kim escreveu:
> Hi Stephane,
> 
> On Tue, 12 Aug 2014 06:44:34 +0200, Stephane Eranian wrote:
> > Hi,
> >
> >
> > My understanding is that the -z option is used to only print a profile
> > since the last refresh. So if I have a refresh of 5s, then it prints the profile
> > based on the samples accumulated over the last 5 seconds.
> 
> Yep, that's what I understand about the -z behavior too.
> 
> >
> > The Z mode used to be available interactively. Nowadays, it seems only
> > avail from the cmdline. But it does not work.
> 
> Hmm.. it seems the stdio supports 'z' key but TUI don't.

Problem introduced long ago when I moved 'top' to use the same hists
browser as 'report', to have all the zooming, --sort, etc goodies.

I see that Namhyung proposed a patch to fix that, will review it,
thanks!

- Arnaldo
 
> >
> > I run a simple test.
> > $ sudo perf top -z
> >
> > Then for 5s I run a cycle-burning noploop program.
> > It shows up at the top. But when it terminates, the program  still stays
> > at the top of the profile for a long time. This is not what I'd expect.
> > The noploop line should disappear in the next couple of refreshes after
> > the program has terminated.
> >
> > I am using tip.git and seeing the problem. But it seems, it's been there for a
> > long time.
> >
> > Any idea what's wrong?
> 
> Looking at the code, it only zero out the annotation info but hist
> entries.  I guess we need to check the flag and throw out existing
> entries instead of decaying.
> 
> Also I wonder about the order of decaying - shouldn't it be decayed
> before processing current entries?  It seems current code processes
> current entries first and then decays...
> 
> I'll prepare patches for this soon.
> 
> Thanks,
> Namhyung
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