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SubjectRe: [PATCH] Radix-tree pagecache for 2.5
Date
Jeff Garzik wrote:
>
> On Fri, Feb 01, 2002 at 09:06:37AM -0800, Linus Torvalds wrote:
> > Even databases often use multiple files, and quite frankly, a database
> > that doesn't use mmap and doesn't try very hard to not cause extra system
> > calls is going to be bad performance-wise _regardless_ of any page cache
> > locking.
>
> I've always thought that read(2) and write(2) would in the end wind up
> faster than mmap(2)... Tests in my rewritten cp/rm/mv type utilities
> seem to bear this out.
>
> Is mmap(2) only preferred for large files/databases?

I've tried to make faster md5summing program and programmed several
ways of accessing file - for the very large files the fastest
way seemed to be O_DIRECT with threaded precaching.

For fast mmap access I'd to implement two parallel mmpad areas with
madvise MADV_WILLNEED - then it was almost as fast as read


--
.''`. Which fundamental human right do you want to give up today?
: :' : Debian GNU/Linux maintainer - www.debian.{org,cz}
`. `' Zdenek Kabelac kabi@{debian.org, users.sf.net, fi.muni.cz}
`- When in doubt, just blame the Euro. :)

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