Re: Possible optimization in ext2_file_write()

["Stephen C. Tweedie" <sct@redhat.com>]

Hi,

On Thu, 18 Mar 1999 23:46:57 +0530 (IST), V Ganesh
<ganesh@vxindia.veritas.com> said:

> 	it looks like whenever we write a partial block which 
> doesn't exist in the buffer cache, ext2_file_write() (and
> possibly the write functions of other filesystems) directly
> reads that block from the block device without checking if
> it is present in the page cache. 

Correct...

> Of course, typical UNIX programs/shell jobs don't indulge in
> this kind of behaviour. General workstation usage (X,
> kernel compiles etc.) for a day caused only 32 unnecessary
> reads. 

... and also correct.

> So unless there are any specific application categories which
> require this I guess it's not worth the trouble to patch.

I'd agree (strongly).  It ties in with your next question:

> Anyone working on a VM revamp or buffer/page cache unification ?

Yes.  We still need the buffer cache (or something very like it) for
filesystem metadata caching and for block IO.  However, 2.3 _will_ see
us using the page cache for data writeback (and we already have
prototype patches to support that sort of behaviour).  The linux-mm
list has been discussing it for some time.

--Stephen
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