Re: [PATCH] 2.4.20-rmap15a

Willy Tarreau (willy@w.ods.org)
Mon, 2 Dec 2002 21:45:09 +0100


On Mon, Dec 02, 2002 at 10:38:40AM -0200, Rik van Riel wrote:
> OK, do you have a better idea on how to implement this thing ?

Hello !

Please excuse my ignorance of the internals, but from a neutral view, I think
that an efficient design could be like this :
- not one, but two elevators, one for read requests, one for write requests.
- may be one couple of these elevators for each physical device to ease
parallelism, but I'm not sure.
- we would process one of the request queues (either reads or writes), and
after a user-settable amount of requests processed, we would switch to the
other one if it contains pending requests. For each request processed, we
would take a look at the other queue, to see if a request for a very close
location exists, in which case we would also switch.

This would bring the advantage of the latency/throughput balance being
completely user-settable.

Please excuse me if it's impossible in the current design or if it's already
done this way and fails. I just wanted to add my 2 euro-cents here.

Comments ?

Cheers,
Willy

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