linux-kernel - Re: [PATCH] perf wrong branches event on AMD

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Message-ID: <1278070727.1917.253.camel@laptop>
Date:	Fri, 02 Jul 2010 13:38:47 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Vince Weaver <vweaver1@...s.utk.edu>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH] perf wrong branches event on AMD

On Thu, 2010-07-01 at 15:30 -0400, Vince Weaver wrote:
> This is why event selection needs to be in user-space... it could be fixed 
> instantly there, but the way things are done now it will take months to 
> years for this fix to filter down to those trying to use perf counters...

Last time I checked apt-get upgrade/yum upgrade simply upgraded
everything, including kernels.. (and upgrades to userspace packages can
take months too)

Someone needs to build a new package and publish it, upgrading the
kernel is no harder than upgrading any other.

If you don't want to reboot, there's the -r option Arnaldo already
mentioned. There's also the option of writing a kernel module to poke at
the data table if you really really want to update a running kernel.

If you think this is a really "important" feature you could even make a
patch that exposes all these data tables to userspace through sysfs or
whatever and see if people think its worth the effort.

Personally I don't think people will ever use such a sysfs interface,
but hey, that's my opinion.
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