linux-kernel - Re: [PATCH] x86: Intel microcode loader performance improvement

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Message-ID: <4B94DE1A.40807@redhat.com>
Date:	Mon, 08 Mar 2010 13:23:06 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Dmitry Adamushko <dmitry.adamushko@...il.com>
CC:	Dimitri Sivanich <sivanich@....com>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] x86: Intel microcode loader performance improvement

On 03/08/2010 12:33 PM, Dmitry Adamushko wrote:
> On 5 March 2010 18:42, Dimitri Sivanich<sivanich@....com>  wrote:
>    
>> We've noticed that on large SGI UV system configurations, running
>> microcode.ctl can take very long periods of time.  This is due to
>> the large number of vmalloc/vfree calls made by the Intel
>> generic_load_microcode() logic.
>>
>> By reusing allocated space, the following patch reduces the time
>> to run microcode.ctl on a 1024 cpu system from approximately 80
>> seconds down to 1 or 2 seconds.
>>
>> Signed-off-by: Dimitri Sivanich<sivanich@....com>
>>      
> This approach seems reasonable in the scope of the current framework.
>
> Acked-by: Dmitry Adamushko<dmitry.adamushko@...il.com>
>
> However, I think a better approach would be to have some kind of
> shared storage for loaded microcode updates. Given that for the
> majority of SMP systems all the cpus are normally updated to the very
> same new instance of microcode, it should be enough to do a search for
> the first cpu, cache the instance of microcode and then reuse it for
> others.
>
>    

And/or update processors in parallel.

-- 
error compiling committee.c: too many arguments to function

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