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SubjectRe: More on 2.2.18pre2aa2
On Tue, 12 Sep 2000, Alan Cox wrote:

>Andrea - latency is time measured and perceived. Doing it time based seems to
>make reasonable sense. I grant you might want to play with the weighting per

When you have a device that writes a request every two seconds you still
want it not to seek all the time because this would mean to make it even
slower. No? The point very is simple: if you want good latency buy a
faster hardware (and with a faster hardware our current elevator can
become even more aggressive than the 1/2 second thing). You can't
workaround the slowness of a slow device by putting the elevator in
function of time, that will only make the global system even slower.

BTW, about the rest of the proposal we're just doing that. It's just that
we don't do that in function of time, but in function of how many requests
are passing a certain request. When too many request passed a certain
request, we stop further requests to pass it again. Simple. You control
the "how many request can pass a request" factor via elvtune. Read and
writes have different factors.


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