From: Dave Jones <davej@redhat.com>
To: Alexey Dobriyan <adobriyan@openvz.org>
Cc: cpufreq@lists.linux.org.uk, devel@openvz.org
Subject: Re: rdmsr_on_cpu, wrmsr_on_cpu et al
Date: Wed, 17 Jan 2007 20:01:34 -0500 [thread overview]
Message-ID: <20070118010134.GB31366@redhat.com> (raw)
In-Reply-To: <20070117132613.GC6021@localhost.sw.ru>
On Wed, Jan 17, 2007 at 04:26:13PM +0300, Alexey Dobriyan wrote:
> Hi, Dave!
>
> There was OpenVZ specific bug rendering some cpufreq drivers unusable
> on SMP. In short, when cpufreq code thinks it confined itself to
> needed cpu by means of set_cpus_allowed() to execute rdmsr, some
> "virtual cpu" feature can migrate process to anywhere. This triggers
> bugons and does wrong things in general.
>
> This got fixed by introducing rdmsr_on_cpu and wrmsr_on_cpu executing
> rdmsr and wrmsr on given physical cpu by means of smp_call_function_single().
>
> So, understanding p4-clockmod is not the only driver that was affected,
> is something like this acceptable for start?
This is probably useful outside of cpufreq too, so should probably
go somewhere in include/asm/processor.h for eg.
Looks ok on a quick glance, but I'd like to see if anyone on lkml
has any comments, especially the usual x86/x86-64 experts.
Dave
--
http://www.codemonkey.org.uk
prev parent reply other threads:[~2007-01-18 1:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-17 13:26 rdmsr_on_cpu, wrmsr_on_cpu et al Alexey Dobriyan
2007-01-18 1:01 ` Dave Jones [this message]
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