Re: [Qemu-devel] [RFC PATCH 3/3] qemu-coroutine: use a ring per thread for the pool

[Peter Lieven]

Am 28.11.2014 um 12:23 schrieb Paolo Bonzini:
>
> On 28/11/2014 12:21, Peter Lieven wrote:
>> Am 28.11.2014 um 12:14 schrieb Paolo Bonzini:
>>>> master:
>>>> Run operation 40000000 iterations 12.851414 s, 3112K operations/s, 321ns 
>>>> per coroutine
>>>>
>>>> paolo:
>>>> Run operation 40000000 iterations 11.951720 s, 3346K operations/s, 298ns 
>>>> per coroutine
>>> Nice. :)
>>>
>>> Can you please try "coroutine: Use __thread … " together, too?  I still
>>> see 11% time spent in pthread_getspecific, and I get ~10% more indeed if
>>> I apply it here (my times are 191/160/145).
>> indeed:
>>
>> Run operation 40000000 iterations 10.138684 s, 3945K operations/s, 253ns per 
>> coroutine
> Your perf_master2 uses the ring buffer unconditionally, right?  I wonder
> if we can use a similar algorithm but with arrays instead of lists...

You mean an algorithm similar to perf_master2 or to the current implementation?

The ring buffer seems to have a drawback when it comes to excessive coroutine 
nesting.
My idea was that you do not throw away hot coroutines when the pool is full. 
However,
i do not know if this is really a problem since the pool is only full when 
there is not much
I/O. Or is this assumption to easy?

Peter