Messages in this thread | | | Subject | Re: [PATCH] deadline io scheduler | From | Daniel Pittman <> | Date | Thu, 26 Sep 2002 18:28:01 +1000 |
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On Thu, 26 Sep 2002, Jens Axboe wrote: > On Wed, Sep 25 2002, Andrew Morton wrote:
[...]
> writes_starved. This controls how many times reads get preferred over > writes. The default is 2, which means that we can serve two batches of > reads over one write batch. A value of 4 would mean that reads could > skip ahead of writes 4 times. A value of 1 would give you 1:1 > read:write, ie no read preference. A silly value of 0 would give you > write preference, always.
Actually, a value of zero doesn't sound completely silly to me, right now, since I have been doing a lot of thinking about video capture recently.
How much is it going to hurt a filesystem like ext[23] if that value is set to zero while doing large streaming writes -- something like (almost) uncompressed video at ten to twenty meg a second, for gigabytes?
This is a situation where, for a dedicated machine, delaying reads almost forever is actually a valuable thing. At least, valuable until it stops the writes from being able to proceed.
Daniel
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