| Date | Tue, 6 Oct 2015 09:39:28 +0100 | Subject | Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit | From | Linus Torvalds <> |
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On Tue, Oct 6, 2015 at 1:47 AM, Andy Lutomirski <luto@kernel.org> wrote: > > The patchset is structured as a removal of the old fast syscall > code, then the change that makes syscalls into real functions, then > a clean re-implementation of fast syscalls. > > If we want some of the 25 cycles back, we could consider open-coding > a new C fast path.
Ok, the 25 cycles are apparently just 12 cycles. Did you forget to update that after doing some of the optimizations - or is it 25 cycles on 64-bit and 12 cycles on 32-bit?
But regardless, I've read through the series twice, and I don't see anything wrong. The one thing I thought I noticed ended up being mooted by a patch later in the series.
Of course, this is the kind of code where reading the patch doesn't necessarily catch any of the really subtle problems at all, but you seem to have tested it fairly heavily too.
So ACK on the whole series. I don't mind a few cycles for the fast case if it means it's more maintainable, and sadly I suspect that with so many distributions using audit functionality, the fast case is almost unheard of anyway, and the fact that you sped up the slow case is what matters more. Snif.
I'd like to see this as a git tree, with your longish explanation as the pull request for the x86 merge, so that that gets saved for posterity too in the kernel commit logs. But that's between you and Ingo or whoever ends up being the person who picks this up.
Linus
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