* Andy Lutomirski <[email protected]> wrote:
> On Fri, Oct 9, 2015 at 12:32 AM, Ingo Molnar <[email protected]> wrote:
> >
> > * Andy Lutomirski <[email protected]> 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.
So the perf bench stuff is meant to be a familiar home to kernel developers
we'd
like to slap a micro (or macro) benchmark into an easy to modify place.
Over the years it has gathered a number of benchmarks - but more are always
welcome.
Just copy one of the existing benchmark modules (the tools/perf/bench/numa.c
one
is the most advanced one, tools/perf/bench/sched-pipe.c is the simplest one)
and
off you go.
Here's a commit that adds a new benchmark suite:
a043971141f1 ("perf bench: Add futex-hash microbenchmark")
There are no big restrictions on the benchmarks: just put your existing code in
that produces stdout output and it will be likely very close to upstream
acceptable.
Can help should you get stuck anywhere.
Thanks,
Ingo
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