| From | Andy Lutomirski <> | Date | Tue, 6 Oct 2015 11:26:43 -0700 | Subject | Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit |
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On Oct 6, 2015 1:39 AM, "Linus Torvalds" <torvalds@linux-foundation.org> wrote: > > 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?
Forgot to update. I'll fix this in v3. I'll also re-benchmark on native 32-bit, which is a bit easier now that I figured out why my Debian VM couldn't do fast syscalls. (Hint: if you have a 32-bit Debian or Debian-derived setup without libc6-i686 installed, install it and everything works better.)
--Andy
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