Re: [PATCH] cfq-prio #2

[Nick Piggin <piggin@cyberone.com.au>]

Jens Axboe wrote:

>On Tue, Nov 11 2003, Nick Piggin wrote:
>
>>
>>Jens Axboe wrote:
>>
>>
>>>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.