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

[Marcelo Tosatti]

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);
 }

 /*