Re: clustering page-ins

Chuck Lever (cel@monkey.org)
Thu, 12 Aug 1999 21:18:56 -0400 (EDT)

On Thu, 12 Aug 1999, Dr. Michael Weller wrote:
> I didn't try the already posted patches, but if it is not already the case
> I'd suggest to make the behaviour configurable by madvice, you know:
>
> I was told somehow the origins of this function might be BSD, so it might
> be worthwhile to support. I saw it in many unixes but it is usually
> documented to have no effect at all.

someone (randy appleton?) is already looking at adding madvise(). i hope
the work i'm doing doesn't make his work more difficult to implement.

FreeBSD has madvise() and adjusts its read-around depending on the
application's suggested access pattern. it doesn't appear that it has any
sophisticated guessing heuristics about whether an application is
accessing in sequential or random order.

interestingly, though, it appears that FreeBSD's read() simply does
clustered reads rather than any complicated read-ahead. but i could be
wrong about that.

- Chuck Lever

--
corporate:	<chuckl@netscape.com>
personal:	<chucklever@netscape.net> or <cel@monkey.org>


The Linux Scalability project:
	http://www.citi.umich.edu/projects/linux-scalability/




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