Re: fio posixaio performance problem

[Jens Axboe]

On 2011-08-04 10:35, Gui Jianfeng wrote:
>> looks the system does a write in every 8ms. This is quite wrong. does
>> the posixaio
>> engine have something wrong? can you use a new fio or try libaio please.
> 
> Yes, I also highly suspect that fio's posixaio engine works bad.
> On the other hand, I'm not sure why preempting in cfqs doesn't happen.
> It seems requests from different threads is close enough...

Can't be ruled out that there's a bug in the posixaio engine. It's
perhaps 100 lines of interesting code in there, so should be easy enough
to audit. Unless it's an interaction with the fio core of course.

Since you're using a queue depth of 1, every getevents call would end up
in aio_suspend() waiting for the previously submitted one. That should
interleave just fine with the other threads, though.

-- 
Jens Axboe

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