Re: [patch] preemptive kernel, preemptive-2.3.52-A7

From: Arjan van de Ven (arjan@fenrus.demon.nl)
Date: Wed Mar 29 2000 - 12:25:07 EST


In article <20000329093127.C27237@hq.fsmlabs.com> you wrote:
> If read/write is too slow, figuring out some way to force it into
> mmap or do something else smart is an alternative to checking needs
> resched.

Or "just" do the same thing the mm system does: work in chunks with the size
as specified in /proc/sys/vm/page-cluster. This is a relatively small size
(typically 32Kb to 64Kb) and is supposed to be set to a value the harddisk
is comfortable with (read: no more than half the cache-size on the disk).
I remember a discussion around the 2.1.125 time that stated that clustering
in blocks of 32Kb almost doubled the throughtput of hdd's in that time, but
that larger blocks decreased performance.. write() could schedule (or attempt
to if needed) after such a block. I hope this will be good for both hdd
throughput and latency...

Greetings,
   Arjan van de Ven

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