Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 27 Nov 2018 14:50:05 -0800 | Subject | Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression |
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On Tue, Nov 27, 2018 at 12:57 PM Andrea Arcangeli <aarcange@redhat.com> wrote: > > This difference can only happen with defrag=always, and that's not the > current upstream default.
Ok, thanks. That makes it a bit less critical.
> That MADV_HUGEPAGE causes flights with NUMA balancing is not great > indeed, qemu needs NUMA locality too, but then the badness caused by > __GFP_THISNODE was a larger regression in the worst case for qemu. [...] > So the short term alternative again would be the alternate patch that > does __GFP_THISNODE|GFP_ONLY_COMPACT appended below.
Sounds like we should probably do this. Particularly since Vlastimil pointed out that we'd otherwise have issues with the back-port for 4.4 where that "defrag=always" was the default.
The patch doesn't look horrible, and it directly addresses this particular issue.
Is there some reason we wouldn't want to do it?
Linus
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