Re: slow io_submit

From: Jens Axboe
Date: Fri Dec 01 2006 - 12:27:42 EST


On Fri, Dec 01 2006, Raz Ben-Jehuda(caro) wrote:
> Jens suparna hello
>
> I have managed to understand why io_submit is sometimes very slow.
> It is because the device is plugged once too many io's are being sent.
> I have conducted a simple test with nr_request to default value of 128
> and and 256.
> and it proved to be correct.

I don't understand your email. The device is plugged when it is empty,
not when it has emptied the request list.

> I would truely appreciate your comment on this.

On what? :-)

If it's no blocking and returning EAGAIN instead, then I agree this is
what should eventually happen. Right now nobody is working on that
afaik, so it's not something that will hit the next kernel.

--
Jens Axboe

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