RE: [patch, CFT] improved disk read latency

From: Giuliano Pochini (pochini@shiny.it)
Date: Mon Jan 07 2002 - 09:20:07 EST


> + if (__rq->elevator_sequence-- <= 0) {
> + /*
> + * OK, we've exceeded someone's latency limit.
> + * But we still continue to look for merges,
> + * because they're so much better than seeks.
> + */
> + merge_only = 1;

That's true for hard discs, but for most removables seek time is
small compared to write time. Think about a magneto-optical drive or
a ZIP. Seek is about 20-50ms while writing goes at 300-1000KiB/s.

Bye.

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