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SubjectRe: [PATCH] cfq-prio #2
On Tue, Nov 11 2003, Nick Piggin wrote:
> >>>>Its quite important. If the queue is full, and AS is waiting for a
> >>>>process
> >>>>to submit a request, its got a long wait.
> >>>>
> >>>>Maybe a lower limit for per process nr_requests. Ie. you may queue if
> >>>>this
> >>>>queue has less than 128 requests _or_ you have less than 8 requests
> >>>>outstanding. This would solve my problem. It would also give you a much
> >>>>more
> >>>>appropriate scaling for server workloads, I think. Still, thats quite a
> >>>>change in behaviour (simple to code though).
> >>>>
> >>>>
> >>>That basically belongs inside your may_queue for the io scheduler, imo.
> >>>
> >>>
> >>You can force it to disallow the request, but you can't force it to allow
> >>one (depending on a successful memory allocation, of course).
> >>
> >
> >Well that's back two mails then, make may_queue return whether you must
> >queue, may queue, or can't queue.
> >
> Yep, sounds good. I'll make a patch for it for 2.6.x > 0 sometime unless
> you beat me to it.

I'll include it in the next cfq patch, then it can be submitted when the
freeze unthaws a bit.

Jens Axboe

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