Re: [patch] swap-speedup-2.4.3-B3 (fwd)

From: Marcelo Tosatti (marcelo@conectiva.com.br)
Date: Fri Apr 27 2001 - 06:45:52 EST


On Fri, 27 Apr 2001, Mike Galbraith wrote:

> On Thu, 26 Apr 2001, Rik van Riel wrote:
>
> > On Thu, 26 Apr 2001, Mike Galbraith wrote:
> >
> > > > > > No. It livelocked on me with almost all active pages exausted.
> > > > > Misspoke.. I didn't try the two mixed. Rik's patch livelocked me.
> > > >
> > > > Interesting. The semantics of my patch are practically the same as
> > > > those of the stock kernel ... can you get the stock kernel to
> > > > livelock on you, too ?
> > >
> > > Generally no. Let kswapd continue to run? Yes, but not always.
> >
> > OK, then I guess we should find out WHY the thing livelocked...
>
> Hi Rik,
>
> I decided to take a break from pondering input and see why the thing
> ran itself into the ground. Methinks I was sent the wrooong patch :)

Mike,

Please apply this patch on top of Rik's v2 patch otherwise you'll get the
livelock easily:

--- linux.orig/mm/vmscan.c Fri Apr 27 04:32:52 2001
+++ linux/mm/vmscan.c Fri Apr 27 04:32:34 2001
@@ -644,6 +644,7 @@
        struct page * page;
        int maxscan = nr_active_pages >> priority;
        int page_active = 0;
+ int start_count = count;

        /*
         * If no count was specified, we do background page aging.
@@ -725,7 +726,7 @@
        }
        spin_unlock(&pagemap_lru_lock);

- return count;
+ return (start_count - count);
 }

 /*

-
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