Messages in this thread Patch in this message | | | Subject | Re: [PATCH 3/3] mm: slub: Default slub_max_order to 0 | From | James Bottomley <> | Date | Thu, 12 May 2011 17:04:41 -0500 |
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On Thu, 2011-05-12 at 15:04 -0500, James Bottomley wrote: > Confirmed, I'm afraid ... I can trigger the problem with all three > patches under PREEMPT. It's not a hang this time, it's just kswapd > taking 100% system time on 1 CPU and it won't calm down after I unload > the system.
Just on a "if you don't know what's wrong poke about and see" basis, I sliced out all the complex logic in sleeping_prematurely() and, as far as I can tell, it cures the problem behaviour. I've loaded up the system, and taken the tar load generator through three runs without producing a spinning kswapd (this is PREEMPT). I'll try with a non-PREEMPT kernel shortly.
What this seems to say is that there's a problem with the complex logic in sleeping_prematurely(). I'm pretty sure hacking up sleeping_prematurely() just to dump all the calculations is the wrong thing to do, but perhaps someone can see what the right thing is ...
By the way, I stripped off all the patches, so this is a plain old 2.6.38.6 kernel with the default FC15 config.
James
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diff --git a/mm/vmscan.c b/mm/vmscan.c index 0665520..1bdea7d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2255,6 +2255,8 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, if (remaining) return true; + return false; + /* Check the watermark levels */ for (i = 0; i < pgdat->nr_zones; i++) { struct zone *zone = pgdat->node_zones + i;
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