Re: [PATCH] cowlinks v2

Jörn Engel
2004-04-05T08:35:59Z

On Sat, 3 April 2004 20:43:44 +0100, Jamie Lokier wrote:
>
> Btw, I'm not suggesting sharing page cache entries.

But I am!!!

Sharing the page cache is more important to me than sharing disk
space. Disk space is cheap, but increasing memory beyond 1GiB in my
notebook is not and 1GiB is too little, so memory is the real
constraint.

And it looks like Pavel already found the solution. Whenever doing
something fishy that would confuse the page cache, we
1. lock
2. invalidate page cache for all files belonging to that cow entity
3. copyfile(), write(), or whatever
4. unlock

This is always possibly, because page cache for cow-files is never
read-write. If it was, we would have done 1-4 before and now have a
regular (non-cow) file.

Did I miss something?

Jörn

--
Premature optimization is the root of all evil.
-- Donald Knuth