Re: [patch] max-sectors-2.6.9-rc1-bk14-A0

Jens Axboe
2004-09-08T11:07:01Z

On Wed, Sep 08 2004, Ingo Molnar wrote:
>
> * Jens Axboe <axboe@suse.de> wrote:
>
> > Wasn't the move of the ide_lock grabbing enough to solve this problem
> > by itself?
>
> yes and no. It does solve it for the specific case of the
> voluntary-preemption patches: there hardirqs can run in separate kernel
> threads which are preemptable (no HARDIRQ_OFFSET). In stock Linux
> hardirqs are not preemptable so the earlier dropping of ide_lock doesnt
> solve the latency.
>
> so in the upstream kernel the only solution is to reduce the size of IO.
> (I'll push the hardirq patches later on too but their acceptance should
> not hinder people in achieving good latencies.) It can be useful for
> other reasons too to reduce IO, so why not? The patch certainly causes
> no overhead anywhere in the block layer and people are happy with it.

I'm not particularly against it, I was just curious. The splitting of
max_sectors into a max_hw_sectors is something we need to do anyways, so
I'm quite fine with the patch. You can add my signed-off-by too.

--
Jens Axboe