Re: [PATCH] 2.6.4-rc2-mm1: vm-split-active-lists

[Nick Piggin]

Andrew Morton wrote:

> Nick Piggin <piggin@xxxxxxxxxxxxxxx> wrote:
>
> > Just had a try of doing things like updatedb and dd if=/dev/zero of=./blah
> > It is pretty swappy I guess.
>
> You'll need to bring the scanning priority back into the picture: don't
> move mapped pages down onto the inactive list at low scanning priorities. 
> And that eans retaining the remember-the-priority-from-last-time logic.
>
> Otherwise it's inevitable that even a `cat monster_file > /dev/null' will
> eventually swap out everything it can.

Hmm I dunno. At mapped_page_cost 8, I don't think it is swappy enough
that your desktop users will be running into problems. I need to write
4GB of file to push out 70MB of swap here (256MB RAM). And not much of
that swap has come back in, by the way...

> > By the way, I would be interested to know the rationale behind
> > mark_page_accessed as it is without this patch, also what is it doing in
> > rmap.c (I know hardly anything actually uses page_test_and_clear_young, but
> > still). It seems to me like it only serves to make VM behaviour harder to
> > understand, but I'm probably missing something. Andrew?
>
> hm, that's left-over code which is pretty pointless now.
>
>
> 	if (page_test_and_clear_young(page))
> 		mark_page_accessed(page);
>
> 	if (TestClearPageReferenced(page))
> 		referenced++;
>
> The pages in here are never on the LRU, so all the mark_page_accessed()
> will do is to set PG_Referenced.  And we immediately clear it again.  So
> the mark_page_accessed() can be replaced with referenced++.

Yep, see the patch I'd attached before.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/