Re: [Qemu-devel] [PATCH v1] test-coroutine: test cost introduced by coroutine

[Gabriel Kerneis]

On 13 août 2014 16:27:29 CEST, "Benoît Canet" <address@hidden> wrote:
> The Wednesday 13 Aug 2014 à 18:08:47 (+0800), Ming Lei wrote :
> > This test runs dummy function with coroutine by using
> > two enter and one yield since which is a common usage.
> > 
> > So we can see the cost introduced by corouting for running
> > one function, for example:
> > 
> >     Run operation 20000000 iterations 4.841071 s, 4131K operations/s
> >     242ns per coroutine
> > 
> > Signed-off-by: Ming Lei <address@hidden>
> > ---
> >  tests/test-coroutine.c |   30 ++++++++++++++++++++++++++++++
> >  1 file changed, 30 insertions(+)
> > 
> > diff --git a/tests/test-coroutine.c b/tests/test-coroutine.c
> > index 6e634f4..e22fae1 100644
> > --- a/tests/test-coroutine.c
> > +++ b/tests/test-coroutine.c
> > @@ -311,6 +311,35 @@ static void perf_baseline(void)
> >          maxcycles, duration);
> >  }
> >  
> > +static __attribute__((noinline)) void perf_cost_func(void *opaque)
> > +{
> > +    qemu_coroutine_yield();
> > +}
> > +
> > +static void perf_cost(void)
> > +{
> > +    const unsigned long maxcycles = 40000000;
> > +    unsigned long i = 0;
> > +    double duration;
> > +    unsigned long ops;
> > +    Coroutine *co;
> > +
> > +    g_test_timer_start();
> > +    while (i++ < maxcycles) {
> > +        co = qemu_coroutine_create(perf_cost_func);
> 
> I am not sure qemu_coroutine_create is systematically used.
> I rather believe the code try to reuse existing coroutine.

Isn't it what the coroutine pool is for? Is there really code duplicating it 
manually? 


> 
> > +        qemu_coroutine_enter(co, &i);
> > +        qemu_coroutine_enter(co, NULL);
> > +    }
> > +    duration = g_test_timer_elapsed();
> > +    ops = (long)(maxcycles / (duration * 1000));
> > +
> > +    g_test_message("Run operation %lu iterations %f s, %luK
> operations/s, "
> > +                   "%luns per coroutine",
> > +                   maxcycles,
> > +                   duration, ops,
> > +                   (unsigned long)(1000000000 * duration) /
> maxcycles);
> > +}
> > +
> >  int main(int argc, char **argv)
> >  {
> >      g_test_init(&argc, &argv, NULL);
> > @@ -325,6 +354,7 @@ int main(int argc, char **argv)
> >          g_test_add_func("/perf/nesting", perf_nesting);
> >          g_test_add_func("/perf/yield", perf_yield);
> >          g_test_add_func("/perf/function-call", perf_baseline);
> > +        g_test_add_func("/perf/cost", perf_cost);
> >      }
> >      return g_test_run();
> >  }
> > -- 
> > 1.7.9.5
> > 
> > 

-- 
Gabriel