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SubjectRe: 2.4.9 VM/VMA subsystem works much better
Date
On August 23, 2001 12:29 pm, Stephan von Krawczynski wrote:
> Daniel Phillips <phillips@bonn-fries.net> wrote:
>
> > On August 22, 2001 09:58 pm, Brad Chapman wrote:
> > > Everyone,
> > >
> > > Just a note: the VMA sanity patch which went in to 2.4.9
> > > has improved Mozilla's performance considerably. I did a rough
> > > calculation based on startup time and found that Mozilla started
> > > approximately 10%-12% faster on 2.4.9 then 2.4.8. Plus, I've
> > > found that swapping is actually starting to work again, although
> > > it still tends to stick at certain times.
> > >
> > > Great job everyone.
> >
> > Make sure you have my SetPageReferenced patch in, swap is borked without
> > it.
>
> Can you send me the patches you think should cure a straight 2.4.9 for
> re-testing (probably the one from Marcelo Tosatti, too).
> I am from the old school: don't believe what you can't test. :-)

I took the liberty of cc'ing this to the list. This patch fixes a severe
swap thrashing problem that was introduced by the use-once patch in 2.4.8. I
explained the details elsewhere. Other than the swap problem (which was just
an oversight, not a design error) the use-once strategy seems to be working
fine. My own anecdotal evidence: before, dpkg --config -a on this box was
effectively a DoS, now I barely notice it while I'm running other
applications.

There should be a similar hole in pagemap_nopage affecting memmapped files,
but nobody has reported it yet. I presume this is because it's a lot harder
to trigger. I'll supply a patch after I've looked at it a little more.

--- ../2.4.9.clean/mm/memory.c Mon Aug 13 19:16:41 2001
+++ ./mm/memory.c Sun Aug 19 21:35:26 2001
@@ -1119,6 +1119,7 @@
*/
return pte_same(*page_table, orig_pte) ? -1 : 1;
}
+ SetPageReferenced(page);
}

/*
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