Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 15 Jun 2020 12:09:58 -0700 | Subject | Re: [gup] 17839856fd: stress-ng.vm-splice.ops_per_sec 2158.6% improvement |
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On Mon, Jun 15, 2020 at 12:33 AM Jann Horn <jannh@google.com> wrote: > > So in summary I guess the test was just really slow up until now > because it was hitting a slowpath that you wouldn't hit during normal > usage? At least for vmsplice(), writing uninitialized pages doesn't > really make a whole lot of sense...
Heh. My main worry with that commit was that we'd see the reverse effect: somebody implicitly depending on the continued sharing of pages in some odd splice situation, and where breaking the COW would result in a performance degradation.
The fact that it went the other way instead is somewhat ironic.
But good.
I guess I'll just ping the stable people to say "yeah, put that in stable too". It's a fix, and apparently it _helps_ performance for the degenerate cases rather than hurting anything.
Linus
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