linux-kernel - Re: [BUG] perf_events: PERF_FORMAT_GROUP not working correctly when monitoring another task

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1273177360.1642.280.camel@laptop>
Date:	Thu, 06 May 2010 22:22:40 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Carl Love <carll@...ibm.com>,
	Maynard Johnson <mpjohn@...ibm.com>,
	stephane eranian <eranian@...glemail.com>
Subject: Re: [BUG] perf_events: PERF_FORMAT_GROUP not working correctly
 when monitoring another task

On Thu, 2010-05-06 at 13:09 -0700, Corey Ashford wrote:
> The patch works with the test case I provided, but for some reason it 
> breaks the normal operation of the libpfm4 "task" utility.  If I put 
> more than one event in a group, I get zero counts on all but the first 
> event.  That's even if I don't use the PERF_FORMAT_GROUP option.

Bugger,.. weird though, I can't see how it would affect the state before
the counters get detached from their context (exit() / close()).

> So something appears to be messed up.  I will see if I can construct an 
> arch-independent test case which demonstrates the problem.

That would be awesome, thanks!


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/