On Thu, Feb 04, 2021 at 01:19:47PM +0800, Xing Zhengjun wrote:
>
>
> On 2/3/2021 10:49 AM, Roman Gushchin wrote:
> > On Tue, Feb 02, 2021 at 04:18:27PM +0800, Xing, Zhengjun wrote:
> > > On 1/14/2021 11:18 AM, Roman Gushchin wrote:
> > > > On Thu, Jan 14, 2021 at 10:51:51AM +0800, kernel test robot wrote:
> > > > > Greeting,
> > > > >
> > > > > FYI, we noticed a -62.4% regression of hackbench.throughput due to
> > > > > commit:
> > > > Hi!
> > > >
> > > > Commit "mm: memcg/slab: optimize objcg stock draining" (currently only
> > > > in the mm tree,
> > > > so no stable hash) should improve the hackbench regression.
> > > The commit has been merged into Linux mainline :
> > > 3de7d4f25a7438f09fef4e71ef111f1805cd8e7c ("mm: memcg/slab: optimize
> > > objcg
> > > stock draining")
> > > I test the regression still existed.
> > Hm, so in your setup it's about the same with and without this commit?
> >
> > It's strange because I've received a letter stating a 45.2% improvement
> > recently:
> > https://lkml.org/lkml/2021/1/27/83
>
> They are different test cases, 45.2% improvement test case run in "thread"
> mode, -62.4% regression test case run in "process" mode.
Thank you for the clarification!
> From 286e04b8ed7a0427 to 3de7d4f25a7438f09fef4e71ef1 there are two
> regressions for process mode :
> 1) 286e04b8ed7a0427 to 10befea91b61c4e2c2d1df06a2e (-62.4% regression)
> 2) 10befea91b61c4e2c2d1df06a2e to d3921cb8be29ce5668c64e23ffd (-22.3%
> regression)
>
> 3de7d4f25a7438f09fef4e71ef111f1805cd8e7c only fix the regression 2) , so the
> value of "hackbench.throughput" for 3de7d4f25a7438f09fef4e71ef1(71824) and
> 10befea91b61c4e2c2d1df06a2e (72220) is very closed.
Ok, it seems that 1) is caused by switching to per-object accounting/stats of
slab memory.
I don't now anything about 2). There are 38326 commits in between. Do you know
which commits
are causing it?
I believe that 3de7d4f25a74 partially fixes regression 1).
I'll take a look what we can do here.
Some regression could be unavoidable: we're doing more precise accounting, but
it requires
more work. As a compensation we're getting major benefits like saving over 40%
of
the slab memory and having less fragmentation.
But hopefully we can make it smaller.
Thanks!
