Messages in this thread | | | Date | Fri, 9 Oct 2015 09:32:06 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch |
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* Andy Lutomirski <luto@kernel.org> wrote:
> we're following a 32-bit pointer, and the uaccess code isn't smart > enough to figure out that the access_ok check isn't needed. > > This saves about three cycles on a cache-hot fast syscall.
Another request: could you please stick the benchmarking code of the various x86 system call variants into 'perf bench' - under tools/perf/bench/, so that measurements can be done on more hardware and can be reproduced easily?
I'd suggest we dedicate an entirely new benchmark family to it: 'perf bench x86' and then have:
perf bench x86 syscall vdso perf bench x86 syscall int80 perf bench x86 syscall vdso-compat
or so?
( I have some perf bench cleanups in -tip, so if you do this please base it on top of that. )
Thanks,
Ingo
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