Re: [mm] 23047a96d7: vm-scalability.throughput -23.8% regression

[Johannes Weiner]

Hi,

thanks for your report.

On Tue, May 17, 2016 at 12:58:05PM +0800, kernel test robot wrote:
> FYI, we noticed vm-scalability.throughput -23.8% regression due to commit:
> 
> commit 23047a96d7cfcfca1a6d026ecaec526ea4803e9e ("mm: workingset: per-cgroup cache thrash detection")
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> 
> in testcase: vm-scalability
> on test machine: lkp-hsw01: 56 threads Grantley Haswell-EP with 64G memory
> with following conditions: cpufreq_governor=performance/runtime=300s/test=lru-file-readtwice

That test hammers the LRU activation path, to which this patch added
the cgroup lookup and pinning code. Does the following patch help?