Re: [PATCH 0/5] Reduce GFP_ATOMIC allocation failures, candidate fix V3

[Mel Gorman <mel-wPRd99KPJ+uzQB+pC5nmwQ@public.gmane.org>]

On Sun, Nov 15, 2009 at 01:07:21PM +0100, Karol Lewandowski wrote:
> On Thu, Nov 12, 2009 at 07:30:30PM +0000, Mel Gorman wrote:
> 
> > [Bug #14265] ifconfig: page allocation failure. order:5, mode:0x8020 w/ e100
> 
> > Patches 1-3 should be tested first. The testing I've done shows that the
> > page allocator and behaviour of congestion_wait() is more in line with
> > 2.6.30 than the vanilla kernels.
> > 
> > It'd be nice to have 2 more tests, applying each patch on top noting any
> > behaviour change. i.e. ideally there would be results for
> > 
> >  o patches 1+2+3
> >  o patches 1+2+3+4
> >  o patches 1+2+3+4+5
> > 
> > Of course, any tests results are welcome. The rest of the mail is the
> > results of my own tests.
> 
> I've tried testing 3+4+5 against 2.6.32-rc7 (1+2 seem to be in
> mainline) and got failure.  I've noticed something strange (I think).
> I was unable to trigger failures when system was under heavy memory
> pressure (i.e. my testing - gitk, firefoxes, etc.).  When I killed
> almost all memory hogs, put system into sleep and resumed -- it
> failed.  free(1) showed:
> 
>              total       used       free     shared    buffers     cached
> Mem:        255240     194052      61188          0       4040      49364
> -/+ buffers/cache:     140648     114592
> Swap:       514040      72712     441328
> 
> 
> Is that ok?  Wild guess -- maybe kswapd doesn't take fragmentation (or
> other factors) into account as hard as it used to in 2.6.30?
> 

That's a lot of memory free. I take it the order-5 GFP_ATOMIC allocation
failed. What was the dmesg for it please?

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