| From | Andy Lutomirski <> | Date | Fri, 9 Oct 2015 12:28:46 -0700 | Subject | Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch |
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On Fri, Oct 9, 2015 at 12:32 AM, Ingo Molnar <mingo@kernel.org> wrote: > > * 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
I'll play with this. I'm not too familiar with the perf bench stuff.
--Andy
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