Re: [Qemu-devel] [PATCH] test-coroutine: add baseline test that times the cost of function calls

[Stefan Hajnoczi]

On Wed, Aug 06, 2014 at 11:33:41AM +0200, Paolo Bonzini wrote:
> This can be used to compute the cost of coroutine operations.  In the
> end the cost of the function call is a few clock cycles, so it's pretty
> cheap for now, but it may become more relevant as the coroutine code
> is optimized.
> 
> For example, here are the results on my machine:
> 
>    Function call 100000000 iterations: 0.173884 s
>    Yield 100000000 iterations: 8.445064 s
>    Lifecycle 1000000 iterations: 0.098445 s
>    Nesting 10000 iterations of 1000 depth each: 7.406431 s
> 
> One yield takes 83 nanoseconds, one enter takes 97 nanoseconds,
> one coroutine allocation takes (roughly, since some of the allocations
> in the nesting test do hit the pool) 739 nanoseconds:
> 
>    (8.445064 - 0.173884) * 10^9 / 100000000 = 82.7
>    (0.098445 * 100 - 0.173884) * 10^9 / 100000000 = 96.7
>    (7.406431 * 10 - 0.173884) * 10^9 / 100000000 = 738.9
> 
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  tests/test-coroutine.c | 24 ++++++++++++++++
>  1 files changed, 24 insertions(+)

Can't hurt to have this as a comparison.

Reviewed-by: Stefan Hajnoczi <address@hidden>

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