Messages in this thread | | | Date | Tue, 27 Jul 2004 10:01:27 +0200 | From | Ingo Molnar <> | Subject | Re: [patch] voluntary-preempt-2.6.8-rc2-J4 |
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[i've sent a second patch too since the first version.]
* Jens Axboe <axboe@suse.de> wrote:
> I don't like it. First of all, the implementation really should drain > the queue first, then set max value before allowing people to queue > more io. The queue lock doesn't help here, readers don't even attempt > to serialize access to max_sectors.
why should the queue be drained? There might be a few leftover big requests, but these are not a problem.
> Secondly, I don't like the concept of exposing this value. If you want > to do something like this, we must split the value into two like > proposed (and patched) some months ago into a hardware and user value.
yes, agreed - that's what the second patch does.
> I don't see why we can't just drop ata48 default value to 256kb > instead. There's very little command over head on ide, I bet the > majority of the change in performance when playing with 256kb vs > 1024kb is not the command overhead itself, rather things like > read-ahead that could be more intelligent.
256kb isnt enough from a latency POV either - and if a user wants some extreme setting like 16KB per request why not allow it? Especially since these tunables cause zero runtime overhead.
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