From: "H. Peter Anvin" <hpa@zytor.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: mingo@redhat.com, acme@redhat.com, paulus@samba.org,
linux-kernel@vger.kernel.org, tzanussi@gmail.com,
a.p.zijlstra@chello.nl, fweisbec@gmail.com, tglx@linutronix.de,
mingo@elte.hu, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:perf/core] perf: Use read() instead of lseek() in trace_event_read.c:skip()
Date: Thu, 20 May 2010 06:41:50 -0700 [thread overview]
Message-ID: <4BF53C1E.9040305@zytor.com> (raw)
In-Reply-To: <AANLkTikqkbScJOVxynoOzejKnaNIucrAczgtGIDqXLCO@mail.gmail.com>
On 05/20/2010 06:39 AM, Pekka Enberg wrote:
> On Thu, May 20, 2010 at 3:54 PM, tip-bot for Tom Zanussi
> <tzanussi@gmail.com> wrote:
>> Commit-ID: cbb5cf7ff6b298beacfe23db3386335b0b9c0a2d
>> Gitweb: http://git.kernel.org/tip/cbb5cf7ff6b298beacfe23db3386335b0b9c0a2d
>> Author: Tom Zanussi <tzanussi@gmail.com>
>> AuthorDate: Tue, 4 May 2010 23:02:10 -0500
>> Committer: Frederic Weisbecker <fweisbec@gmail.com>
>> CommitDate: Thu, 20 May 2010 08:37:17 +0200
>>
>> perf: Use read() instead of lseek() in trace_event_read.c:skip()
>>
>> This is a small fix for a problem affecting live-mode, introduced
>> recently:
>>
>> root@tropicana:~# perf trace rwtop
>> perf trace started with Perl
>> script /root/libexec/perf-core/scripts/perl/rwtop.pl
>>
>> Fatal: did not read header event
>>
>> commit d00a47cce569a3e660a8c9de5d57af28d6a9f0f7 added a skip()
>> function to skip over e.g. header_page, but this doesn't work for
>> live mode. This patch re-implements skip() to use read() instead of
>> lseek() to fix that.
>
> Out of curiosity: why doesn't lseek() work and why can't we fix that?
Presumably because we're reading from a nonseekable stream?
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2010-05-20 13:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-05 4:02 [PATCH] perf/trace: use read() instead of lseek() in trace_event_read.c:skip() Tom Zanussi
2010-05-14 16:12 ` Borislav Petkov
2010-05-14 16:22 ` Frederic Weisbecker
2010-05-20 12:54 ` [tip:perf/core] perf: Use " tip-bot for Tom Zanussi
2010-05-20 13:39 ` Pekka Enberg
2010-05-20 13:41 ` H. Peter Anvin [this message]
2010-05-20 13:43 ` Frederic Weisbecker
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