On Sat, Jun 30, 2012 at 2:53 AM, Peter Zijlstra [off-list ref] wrote:

On Fri, 2012-06-29 at 12:51 -0400, Dor Laor wrote:

quoted

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
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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