Re: [PATCH 3/3] vmscan: Force kswapd to take notice faster whenhigh-order watermarks are being hit

From: Mel Gorman
Date: Mon Nov 02 2009 - 12:38:48 EST

On Mon, Nov 02, 2009 at 06:32:54PM +0100, Frans Pop wrote:
> On Monday 02 November 2009, Mel Gorman wrote:
> > vmscan: Help debug kswapd issues by counting number of rewakeups and
> > premature sleeps
> >
> > There is a growing amount of anedotal evidence that high-order atomic
> > allocation failures have been increasing since 2.6.31-rc1. The two
> > strongest possibilities are a marked increase in the number of
> > GFP_ATOMIC allocations and alterations in timing. Debugging printk
> > patches have shown for example that kswapd is sleeping for shorter
> > intervals and going to sleep when watermarks are still not being met.
> >
> > This patch adds two kswapd counters to help identify if timing is an
> > issue. The first counter kswapd_highorder_rewakeup counts the number of
> > times that kswapd stops reclaiming at one order and restarts at a higher
> > order. The second counter kswapd_slept_prematurely counts the number of
> > times kswapd went to sleep when the high watermark was not met.
> What testing would you like done with this patch?

Same reproduction as before except post what the contents of
/proc/vmstat were after the problem was triggered.


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