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

Frans Pop
2009-11-02T17:32:57Z

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?