| Re: rdmsr_on_cpu, wrmsr_on_cpu et al [message #9702 is a reply to message #9695] |
Thu, 18 January 2007 01:01  |
Dave Jones
Messages: 2
Registered: September 2006
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Junior Member |
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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
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