Re: [PATCH 13/40] autonuma: CPU follow memory algorithm

[Nai Xia <nai.xia@gmail.com>]

On Sat, Jun 30, 2012 at 4:01 AM, Nai Xia <nai.xia@gmail.com> wrote:
> On Sat, Jun 30, 2012 at 2:53 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>> On Fri, 2012-06-29 at 12:51 -0400, Dor Laor wrote:
>>> The previous comments were not shouts but the mother of all NAKs.
>>
>> I never said any such thing. I just said why should I bother reading
>> your stuff if you're ignoring most my feedback anyway.
>>
>> If you want to read that as a NAK, not my problem.
>
> Hey guys, Can I say NAK to these patches ?
>
> Now I aware that this sampling algorithm is completely broken, if we take
> a few seconds to see what it is trying to solve:
>
> We all know that LRU is try to solve the question of "what are the
> pages recently accessed?",
> so its engouth to use pte bits to approximate.
>
> However, the numa balancing problem is fundamentally like this:
>
> In some time unit,
>
>      W = pages_accessed  *  average_page_access_frequence
>
> We are trying to move process to the node having max W,  right?
>
> Andrea's patch can only approximate the pages_accessed number in a
> time unit(scan interval),
> I don't think it can catch even 1% of  average_page_access_frequence
> on a busy workload.
> Blindly assuming that all the pages'  average_page_access_frequence is

Oh, sorry for my typo,  I mean "frequency".


> the same is seemly
> broken to me.
>
> Sometimes, it's good to have a good view of your problem before
> spending a lot time coding.
>
>>
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