Messages in this thread | | | From | "Stephen C. Tweedie" <> | Date | Wed, 26 May 1999 17:26:57 +0100 (BST) | Subject | Re: Buffer Cache API |
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Hi,
On Sat, 22 May 1999 22:02:38 -0400 (EDT), Randy Appleton <randy@euclid.acs.NMU.EDU> said:
> At the LinuxExpo I talked to you about an API allowing an application to > offer advice to the kernel on expected file usage patterns, so the kernel > might improve the buffer cache behavior. You mentioned that POSIX had a > standard on this.
> I've searched, but have not yet found this standard. Can you offer me a > pointer, even if it's just a person to email?
It was in a recent Usenix ;Login: edition, and it also appears on their web site. See:
http://www.usenix.org/publications/login/standards/22.posix.html
posix_fadvise() takes the options:
{POSIX_FADV_NORMAL} No further special treatment {POSIX_FADV_SEQUENTIAL} Expect sequential references {POSIX_FADV_RANDOM} Expect random references {POSIX_FADV_WILLNEED} Will need the specified range soon {POSIX_FADV_DONTNEED} Don't need the specified range anymore {POSIX_FADV_NOREUSE} Expect data will not be reused once accessed
and can operate on any range of any fd. The WILLNEED/DONTNEED gives cache control (prefetch and discard) over specific address ranges, and the others give hints about the access pattern over the entire file.
It looks like a sensible place to start.
--Stephen
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