Re: [PATCH 1/1] mm: add dirty_highmem option

Bron Gondwana
2007-11-27T01:30:41Z

On Mon, Nov 26, 2007 at 09:53:17AM -0800, Linus Torvalds wrote:
>
>
> On Thu, 22 Nov 2007, Bron Gondwana wrote:
> >
> > This patch includes some code cleanup from Linus and a toggle in
> > /proc/sys/vm/dirty_highmem which can be set to 1 to add the highmem
> > back to the total available memory count.
>
> Just to verify - can you confirm that this "just fixes it" for you?
>
> I think this is the right approach to take, and seems very safe (ie people
> who know that their loads are ok can just set the flag), but I do want to
> verify that there was nothing else going on, and that you now see the same
> performance as you did in 2.6.16?
>
> The other alternative, of course, would be to simply allow the dirty
> percentages to be > 100%, but that's just *odd* ;)

Yes, toggling dirty_highmem "just fixes it" in all our tests. I hadn't
tested it on the production machine yet - but I'm just installing it
there now since it's been running fine on a less important machine for
a few days now.

I did wonder about allowing the dirty percentage to go way up, but that
would have cause "this one goes up to 110%" comments in the sysctl
limits code and people would have thought I was childish. Can't have
that. Much better to have "int one = 1" instead.

Bron.