Messages in this thread | | | Date | Tue, 11 Nov 2003 01:34:16 +1100 | From | Nick Piggin <> | Subject | Re: [PATCH] cfq-prio #2 |
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Jens Axboe wrote:
>On Tue, Nov 11 2003, Nick Piggin wrote: > >> >>Jens Axboe wrote: >> >> >>>Hi, >>> >>> >>> >>Hi Jens >> >> >>>@@ -1553,6 +1559,10 @@ >>> struct io_context *ioc = get_io_context(gfp_mask); >>> >>> spin_lock_irq(q->queue_lock); >>>+ >>>+ if (!elv_may_queue(q, rw)) >>>+ goto out_lock; >>>+ >>> if (rl->count[rw]+1 >= q->nr_requests) { >>> /* >>> * The queue will fill after this allocation, so set it as >>>@@ -1566,15 +1576,12 @@ >>> } >>> } >>> >>>- if (blk_queue_full(q, rw) >>>- && !ioc_batching(ioc) && !elv_may_queue(q, rw)) { >>> >>> >>I know I hijacked elv_may_queue from you... any chance we could seperate >>these so our schedulers can live in peace? ;) >> > >IOW, you completely broke it! I'm just changing it back to the >original. When was this done, btw? Just discovered it when updating the >patch. Pretty annoying... >
You acked the change actually :P I guess it was done in mainline when AS was merged.
> >>Maybe my version should be called elv_force_queue? >> > >I just hate to see more of these, really. The original idea for >may_queue was just that, may this process queue io or not. We can make >it return something else, though, to indicate whether the process must >be able to queue. Is it really needed? >
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).
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