On Mon, Oct 26, 2009 at 06:37:36PM +0100, Tobias Oetiker wrote:

Hi Mel,

I have no done additional tests ... and can report the following

Thursday Mel Gorman wrote:

quoted

  1/5 page allocator: Always wake kswapd when restarting an allocation attempt after direct reclaim failed
  2/5 page allocator: Do not allow interrupts to use ALLOC_HARDER


	These patches correct problems introduced by me during the 2.6.31-rc1
	merge window. The patches were not meant to introduce any functional
	changes but two were missed.

	If your problem goes away with just these two patches applied,
	please tell me.

1+2 do not help

quoted

Test 3: If you are getting allocation failures, try with the following patch

  3/5 vmscan: Force kswapd to take notice faster when high-order watermarks are being hit

	This is a functional change that causes kswapd to notice sooner
	when high-order watermarks have been hit. There have been a number
	of changes in page reclaim since 2.6.30 that might have delayed
	when kswapd kicks in for higher orders

	If your problem goes away with these three patches applied, please
	tell me

1+2+3 do not help either

quoted

Test 4: If you are still getting failures, apply the following
  4/5 page allocator: Pre-emptively wake kswapd when high-order watermarks are hit

	This patch is very heavy handed and pre-emptively kicks kswapd when
	watermarks are hit. It should only be necessary if there has been
	significant changes in the timing and density of page allocations
	from an unknown source. Tobias, this patch is largely aimed at you.
	You reported that with patches 3+4 applied that your problems went
	away. I need to know if patch 3 on its own is enough or if both
	are required

	If your problem goes away with these four patches applied, please
	tell me

3 allone does not help
3+4 does ...

This is a bit surprising.....

Tell me, do you have an Intel IO-MMU on your system by any chance?  It should
be mentioned in either dmesg or lspci -v (please send the full output of
both). If you do have one of these things, I notice they abuse PF_MEMALLOC
which would explain why this patch makes a difference to your testing.

Thanks

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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