Messages in this thread | | | Subject | Re: [PATCH-tip 0/2] locking/rwsem: Rwsem rearchitecture part 2 follow-up patches | From | Waiman Long <> | Date | Wed, 17 Apr 2019 16:30:34 -0400 |
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On 04/17/2019 01:57 AM, Ingo Molnar wrote: > * Waiman Long <longman@redhat.com> wrote: > >> On 04/16/2019 01:37 PM, Peter Zijlstra wrote: >>> On Tue, Apr 16, 2019 at 01:03:10PM -0400, Waiman Long wrote: >>>> On 04/16/2019 10:17 AM, Peter Zijlstra wrote: >>>>> On Tue, Apr 16, 2019 at 09:18:50AM -0400, Waiman Long wrote: >>>>>> On 04/16/2019 09:10 AM, Peter Zijlstra wrote: >>>>>>> On Mon, Apr 15, 2019 at 04:58:27PM -0400, Waiman Long wrote: >>>>>>>> This series contain 2 follow-up patches to alleviate the performance >>>>>>>> regression found in the page_fault1 test of the will-it-scale benchmark. >>>>>>>> This does not recover all the lost performance, but reclaim a sizeable >>>>>>>> portion of it. >>>>>>>> >>>>>>>> The regression was found on an Intel system. I have run the test on >>>>>>>> an AMD system. The regression wasn't seen there. There are only minor >>>>>>>> variations in performance. Perhaps the page fault path is quite different >>>>>>>> between Intel and AMD systems. >>>>>>> Can you please just fold this back into the appropriate patches? Trying >>>>>>> to review all the back and forth is painful. >>>>>> I will send out an update part 2 patch with patch 1 of this series >>>>>> merged into the writer spinning on reader patch. Patch 2 of this series >>>>>> will be a standalone one. >>>>> Hmm, in that case I can fold it back too. So hold off on sending it. >>>>> >>>>> I thought #2 was a fixup for an earlier patch as well. >>>> #2 is a performance fix. >>> Of this patch? >>> >>> 206038 N T Apr 13 Waiman Long (7.5K) ├─>[PATCH v4 11/16] locking/rwsem: Enable readers spinning on writer >>> >>> Fixes should have a Fixes: tag. And if the patch it fixes isn't a commit >>> yet, the patch should be refreshed to not need a fix. >> The original patch isn't wrong. This patch just introduce another idea >> to make it better. That is why I would still like to separate it as a >> distinct patch. > Yeah, I think it's better to have it in two separate patches. Basically > patch #1 has a downside for certain workloads, which the heuristics in > patch #2 improve. That's the only connection between the two patches. > > If we find some other worst-case workload then the split of the commits > would allow more finegrained examination of the effects of these > performance tunings. > > Thanks, > > Ingo
As the part2 patches are still being actively modified, it doesn't look like it will make the next merge window. I am fine with postponing it to 5.3. However, I would like to request the merging of just patch 1 of the part 2 patchset. It fixes a locking selftest problem that was introduced in the part 1 patches.
Thanks, Longman
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