Re: [PATCH for mmotm 0/5] introduce swap-backed-file-mapped count and fix vmscan-change-the-number-of-the-unmapped-files-in-zone-reclaim.patch

[Mel Gorman <mel@csn.ul.ie>]

On Thu, Jun 11, 2009 at 07:42:33PM +0900, KOSAKI Motohiro wrote:
> > On Thu, Jun 11, 2009 at 07:25:09PM +0900, KOSAKI Motohiro wrote:
> > > Recently, Wu Fengguang pointed out vmscan-change-the-number-of-the-unmapped-files-in-zone-reclaim.patch
> > > has underflow problem.
> > > 
> > 
> > Can you drop this aspect of the patchset please? I'm doing a final test
> > on the scan-avoidance heuristic that incorporates this patch and the
> > underflow fix. Ram (the tester of the malloc()-stall) confirms the patch
> > fixes his problem.
> 
> OK.
> insted, I'll join to review your patch :)
> 

Thanks. You should have it now. In particular, I'm interested in hearing you
opinion about patch 1 of the series "Fix malloc() stall in zone_reclaim()
and bring behaviour more in line with expectations V3" and if addresses;

1. Does patch 1 address the problem that first led you to develop the patch
vmscan-change-the-number-of-the-unmapped-files-in-zone-reclaim.patch?

2. Do you think patch 1 should merge with and replace
vmscan-change-the-number-of-the-unmapped-files-in-zone-reclaim.patch?

> > > This patch series introduce new vmstat of swap-backed-file-mapped and fix above
> > > patch by it.
> 

I don't think the patch above needs to be fixed by another counter. At
least, once the underflow was fixed up, it handled the malloc-stall without
additional counters. If we need to account swap-backed-file-mapped, we need
another failure case that it addresses to be sure we're doing the right thing.

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