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Date: Mon, 07 Jan 2002 15:20:07 +0100 (CET)
From: Giuliano Pochini <pochini@shiny.it>
To: Andrew Morton <akpm@zip.com.au>
Subject: RE: [patch, CFT] improved disk read latency
Cc: lkml <linux-kernel@vger.kernel.org>
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> +             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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