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SubjectRE: [patch] new fifo I/O elevator that really does nothing at all
On Mon, Mar 28 2005, Chen, Kenneth W wrote:
> The noop elevator is still too fat for db transaction processing
> workload. Since the db application already merged all blocks before
> sending it down, the I/O presented to the elevator are actually not
> merge-able anymore. Since I/O are also random, we don't want to sort
> them either. However the noop elevator is still doing a linear search
> on the entire list of requests in the queue. A noop elevator after
> all isn't really noop.
> We are proposing a true no-op elevator algorithm, no merge, no
> nothing. Just do first in and first out list management for the I/O
> request. The best name I can come up with is "FIFO". I also piggy
> backed the code onto noop-iosched.c. I can easily pull those code
> into a separate file if people object. Though, I hope Jens is OK with
> it.

Jens Axboe wrote on Tuesday, March 29, 2005 12:06 AM
> It's not quite ok, because you don't honor the insertion point in
> fifo_add_request.

But it is FIFO! Honoring insertion point will break the promises this
elevator made to the user: first in first out.

OK, OK, I won't argue to the death of it :-). I will give this a try.

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