On 10.12.2012 19:01, Mel Gorman wrote:

In this last-minute disaster, I'm not thinking properly at all any more. The
shrink slab disabling should have happened before the loop_again but even
then it's wrong because it's just covering over the problem.

The way order and testorder interact with how balanced is calculated means
that we potentially call shrink_slab() multiple times and that thing is
global in nature and basically uncontrolled. You could argue that we should
only call shrink_slab() if order-0 watermarks are not met but that will
not necessarily prevent kswapd reclaiming too much. It keeps going back
to balance_pgdat needing its list of requirements drawn up and receive
some major surgery and we're not going to do that as a quick hack.

I was about to apply the patch that you sent, and reboot the server, but 
it seems there's no point because the patch is flawed?

Anyway, if and when you have a proper one, I'll be glad to test it for 
you and report results.
-- 
Zlatko

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