Re: VM working much better in 2.4.8 than before

Rik van Riel (riel@conectiva.com.br)
Mon, 13 Aug 2001 12:52:45 -0300 (BRST)


On Mon, 13 Aug 2001, Alan Cox wrote:

> > Yes, those would be the expected effects of use-once, in fact it was
> > "morning after updatedb" question that got me started on it.
>
> updatedb is also absolutely fine if you just work with the existing VM
> and up the inode pressure a little. I'm still very unconvinced by
> use-once.

Use-once has a number of theoretical disadvantages too:

1) newly read in pages are evicted earlier, this means
readahead pages will either evict each other or the
amount of readahead done might need to be shrunk
-- the current readahead code is not prepared for this,
use-once could lead to more disk seeks being done

2) since we add new pages to the inactive list, VM
balancing is faced with a really strange situation ;)

Yes, these things are solvable, but not without redesigning
major parts of the VM balancing to do things which have never
been done before. I'm not sure 2.4 is the time to do that.

regards,

Rik

--
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