linux-kernel - Re: [PATCH] perf: fix broken perf inject -b

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Message-ID: <20120130203653.GD5797@infradead.org>
Date:	Mon, 30 Jan 2012 18:36:54 -0200
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Zhang Yanmin <yanmin_zhang@...ux.intel.com>
Cc:	Stephane Eranian <eranian@...gle.com>,
	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	robert.richter@....com, Avi Kivity <avi@...hat.com>
Subject: Re: [PATCH] perf: fix broken perf inject -b

Em Mon, Jan 30, 2012 at 09:09:17PM +0100, Stephane Eranian escreveu:
> On Mon, Jan 30, 2012 at 9:04 PM, Arnaldo Carvalho de Melo
> <acme@...hat.com> wrote:
> > Em Mon, Jan 30, 2012 at 08:53:26PM +0100, Stephane Eranian escreveu:
> >> On Mon, Jan 30, 2012 at 8:00 PM, Arnaldo Carvalho de Melo
> >> <acme@...hat.com> wrote:
> >> > > >>> @@ -173,6 +178,7 @@ static int perf_event__inject_buildid(struct perf_tool *tool,
> >> > > >>>               goto repipe;
> >> > > >>>       }
> >> > > >>> +     machine->pid = event->ip.pid;
> >> >
> >> > > I noticed that this statement conflicts with perf buildid-list (which
> >> > > I am also fixing for pipe mode).

> >> > > I don't quite understand why, though.

> >> > Have you reached any conclusion about this problem? I haven't looked at
> >> > it in detail, could you please elaborate more?

> >> I ended up removing it. But I am not sure this is correct.
> >> Is the pid used in any way when processing buildids?
> >
> > I can't think of any.
> >
> > The same DSO could conceivably be present in the virtual machine, the
> > host, and in the workstation used for perf report.  We just use the
> > build-id in the perf.data file to find the right symtab.

> Right, so I don't know why it's there...

This comes from a1645ce1:

commit a1645ce12adb6c9cc9e19d7695466204e3f017fe
Author: Zhang, Yanmin <yanmin_zhang@...ux.intel.com>
Date:   Mon Apr 19 13:32:50 2010 +0800

    perf: 'perf kvm' tool for monitoring guest performance from host
    
    Here is the patch of userspace perf tool.
    
    Signed-off-by: Zhang Yanmin <yanmin_zhang@...ux.intel.com>
    Signed-off-by: Avi Kivity <avi@...hat.com>



Zhang, what was the thinking about that pid in the buildid event?

>From what I can see we can just ignore it :-\

- Arnaldo
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