linux-kernel - Re: [PATCH 1/3] perf, tool: Force guest machine definition option

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Date:	Fri, 13 Apr 2012 08:15:17 -0600
From:	David Ahern <dsahern@...il.com>
To:	Jiri Olsa <jolsa@...hat.com>
CC:	acme@...hat.com, a.p.zijlstra@...llo.nl, mingo@...e.hu,
	paulus@...ba.org, cjashfor@...ux.vnet.ibm.com, fweisbec@...il.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] perf, tool: Force guest machine definition option

On 4/13/12 6:41 AM, Jiri Olsa wrote:
> I get same error even on acme's urgent branch.. do you mean
> below one?  It fixes the guest machine lookup for mmap event.
>
> perf kvm: Finding struct machine fails for PERF_RECORD_MMAP
> commit 7fb0a5ee8889488f7568ffddffeb66ddeb50917e
> Author: Nikunj A. Dadhania<nikunj@...ux.vnet.ibm.com>
> Date:   Mon Apr 9 13:52:23 2012 +0530

That's the one I was referring to.

>
> In my case it looks like for some reason the guest buildid DSO
> is not stored in record phase (no hits maybe?), so report won't
> create guest machine record at all and get NULL machine.

I see now -- different problem, but similar in that it's an mmap event 
and the pid is 0.

I need to take my daughter to school and won't get back to this for a 
while but what I am seeing is that on perf-record mmap events are 
generated with pid set to DEFAULT_GUEST_KERNEL_ID = 0 
(machines__create_guest_kernel_maps).

On the report side a machine has not been created for pid of 0, so the 
look up in perf_session__find_machine_for_cpumode fails.

David
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