Re: [Bug #14141] order 2 page allocation failures in iwlagn

From: Frans Pop
Date: Fri Nov 06 2009 - 04:51:50 EST

On Thursday 05 November 2009, Frans Pop wrote:
> On Monday 26 October 2009, Frans Pop wrote:
> > On Tuesday 20 October 2009, Mel Gorman wrote:
> > > I've attached a patch below that should allow us to cheat. When it's
> > > applied, it outputs who called congestion_wait(), how long the
> > > timeout was and how long it waited for. By comparing before and
> > > after sleep times, we should be able to see which of the callers has
> > > significantly changed and if it's something easily addressable.
> >
> > The results from this look fairly interesting (although I may be a bad
> > judge as I don't really know what I'm looking at ;-).
> >
> > I've tested with two kernels:
> > 1) 1 test run
> > 2) + congestion_wait() reverts: 2 test runs
> I've taken another look at the data from this debug patch, resulting in
> these graphs:
> I think the graph may show the reason for the congestion_wait()
> regression. Horizontal axis shows time, vertical axis shows number of
> logged congestion_wait calls per type.

I'm sorry. My initial version had a skewed time axis (showed occurrences
instead of actual time). I've now uploaded a corrected version:

I've also uploaded a second version that shows cumulative delay per type,
which probably gives a better insight:

For both the top chart is without the revert, the bottom one after the
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