Re: [PATCH] fix for VM test9-pre,

Andrea Arcangeli
2000-10-02T19:52:17Z

On Mon, Oct 02, 2000 at 04:28:48PM -0300, Rik van Riel wrote:
> Yup, indeed. I guess we need some extra logic to prevent the
> system from trying to fill all of low memory with dirty
> pages just because all of the highmem pages are free.

A dirty page is allocated in the HIGHMEM immediatly because it's allocated with
GFP_HIGHMEM (see page_cache_alloc() macro). Only the I/O is slower then
(compared to a non highmem machine) because we need bounce buffers for it (and
that trashes mem bus and it makes the I/O slower but it's not a matter of
virtual memory balancing as far I can see).

> Unfortunately, I DID get a few bug reports about
> 2.4.0-test6 and earlier kernels that DID show this
> bug ...

So that may be yet another MM bug, since I remeber Ying said he didn't seen the
bad behaviour in test6.

> I can dig out the bug report if you want ;)

I read one that you sent to TYTSO and I believe classzone should take care of
that highmem problem.

Andrea