linux-kernel - Re: [PATCH] perf tools: Fix ordering with unstable tsc

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] [day] [month] [year] [list]

Message-ID: <20120322152832.GE25820@infradead.org>
Date:	Thu, 22 Mar 2012 12:28:32 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] perf tools: Fix ordering with unstable tsc

Em Thu, Mar 22, 2012 at 01:10:31AM +0100, Frederic Weisbecker escreveu:
> On Wed, Mar 14, 2012 at 04:55:35PM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Sat, Feb 18, 2012 at 05:50:37PM +0100, Frederic Weisbecker escreveu:
> > > +static int alloc_cpus_timestamp_array(struct perf_session *s,
> > > +	if (sample->cpu < s->nr_cpus)

> > Shouldn't we try to robustify this checking against HEADER_NRCPUS (if
> > present)?

> Yeah I thought about that too. I can try to make that working.
> I just thought this was an optimization that I could later add (ie: first
> try to see if the core idea of the patch is accepted).

Right, I deferred that to tglx, but he must be busy as always :-P
 
> Of course the real long term optimization is going to have one file per
> CPU. There, the ordering will be much easier and deterministically
> correct.

Yeah.
 
> > > +		os->last_cpu_timestamp = realloc(os->last_cpu_timestamp,
> > > +						 sizeof(u64) * nr_cpus);
> > If realloc fails we return -ENOMEM, but leak the old buffer.

> Doh! the common trap with realloc...

:-)

> > At some point we can have in the TUI/GUI a way for the user to ask for
> > an specific perf.data file to be processed, if it fails to process due
> > to the above realloc, we'll continue, allowing other perf.data files to
> > be processed, but will have this leak.

> Ok. Will fix.

Thanks!

- Arnaldo
--
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/