Message-ID: <53AAD62D.3030105@gmail.com>
Date: Wed, 25 Jun 2014 08:01:17 -0600
From: David Ahern <dsahern@gmail.com>
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To: Stanislav Fomichev <stfomichev@yandex-team.ru>
CC: Jiri Olsa <jolsa@redhat.com>, linux-kernel@vger.kernel.org,
        a.p.zijlstra@chello.nl, paulus@samba.org, mingo@redhat.com,
        acme@kernel.org, namhyung@kernel.org, artagnon@gmail.com,
        rusty@rustcorp.com.au, bp@suse.de
Subject: Re: [PATCH v4 0/4] perf timechart io mode
References: <1403260191-10079-1-git-send-email-stfomichev@yandex-team.ru> <20140624084113.GC31390@krava.redhat.com> <20140624091022.GE20225@stfomichev-desktop.yandex.net> <20140624165712.GA10114@stfomichev-desktop.yandex.net> <53A9B7A4.9050805@gmail.com> <20140624185134.GB1148@krava.brq.redhat.com> <53A9CB6E.5080104@gmail.com> <20140625112019.GC21788@stfomichev-desktop.yandex.net>
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On 6/25/14, 5:20 AM, Stanislav Fomichev wrote:
>>> maybe we dont need to fail in this case.. seems like it should
>>> not be hard to detect, wanr and recover? ;-)
> The easiest way is just to bail out and don't try to be smart, that's
> what I do now.
>
> Another approach would be to just convert all my consistency
> checks to warnings and skip invalid events (and hope it somehow works). I
> think it makes sense when for some reason we have perf.data which
> is not really consistent but we still want to get something out of it.

If the event type does not make sense how can you trust any other field 
-- like event size?

>
>> seems to me it should not be happening at all. It seems like the head caught
>> the tail and was not properly detected.
> So you mean it perf record's fault?
>

In my cases I am running perf-record. At the end of the session it walks 
the events and in too many cases I see the message:

  0x113f80 [0x8]: failed to process type: 68

So, yes I think something is happening during the record such as the 
writer passing the reader and corrupting the buffers.

David
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