Re: 2.6.38 sbrk regression

From: Andrea Arcangeli
Date: Thu Apr 14 2011 - 11:10:28 EST

On Thu, Apr 14, 2011 at 02:49:14PM +0300, raz ben yehuda wrote:
> Hey Andrea
> Me again. I managed to ftrace ( function graph ) the two kernels. I used
> 2.6.37 and 2.6.39-rc3. The bellow is example for sys_brk calls traces
> from each kernel. As you can see, there is no "single smoking gun"
> here.
> The vm functions durations increased as a whole.
> I repeated the tests from sha1 4e9f64c42d0ba5eb0c78569435ada4c224332ce4
> compared to sha1 152c9ccb75548c027fa3103efa4fa4e19a345449 and it is
> consistent. ~13% performance decrease.

> Can you see any relation to thp that might causes this degradation ?

With compaction and THP off I don't see how it could change

But can you try the THP-33 tag of my aa.git tree, that was based on
2.3.37-rc5 so it'll rule out the whole THP patchset if it doesn't
regress compared to 2.6.37-rc5 vanilla.

git clone --reference linux-2.6 git://
git checkout THP-33

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