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SubjectRe: Read-ahead in kernel
Hi,

On Tue, 23 Apr 1996 18:36:24 +0100 (BST), "J.J. Burgess"
<92jjb@eng.cam.ac.uk> said:

> The current kernels have almost no idea about read ahead.

Not true.

> To implement read_ahead properly, we need code either in the buffer
> cache or ll_rw_blk to a) recognise patterns & b) get this read_ahead
> data & put it somewhere.

Nope, the buffer cache is currently used only for things like
directories and other metadata (and directory reading does its own
readahead anyway, in the fs/ext2fs/ functions). It's the *page cache*
which handles most file data IO, and it supports readahead just fine,
thank you. There's been quite a lot of work done on it in recent
kernels.

Please read linux/mm/filemap.c.

Cheers,
Stephen.
--
Stephen Tweedie <sct@dcs.ed.ac.uk>
Department of Computer Science, Edinburgh University, Scotland.


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