Re: [patch 00/19] VM pageout scalability improvements

[Rik van Riel]

On Mon, 7 Jan 2008 11:07:54 -0800 (PST)
Christoph Lameter <clameter@xxxxxxx> wrote:
> On Fri, 4 Jan 2008, Lee Schermerhorn wrote:
> 
> > We see this on both NUMA and non-NUMA. x86_64 and ia64.  The basic
> > criteria to reproduce is to be able to run thousands [or low 10s of
> > thousands] of tasks, continually increasing the number until the system
> > just goes into reclaim.  Instead of swapping, the system seems to
> > hang--unresponsive from the console, but with "soft lockup" messages
> > spitting out every few seconds...
> 
> Ditto here.

I have some suspicions on what could be causing this.

The most obvious suspect is get_scan_ratio() continuing to return
100 file reclaim, 0 anon reclaim when the file LRUs have already
been reduced to something very small, because reclaiming up to that
point was easy.

I plan to add some code to automatically set the anon reclaim to
100% if (free + file_active + file_inactive <= zone->pages_high),
meaning that reclaiming just file pages will not be able to free
enough pages.

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