Re: [PATCH]vmscan: handle underflow for get_scan_ratio

KOSAKI Motohiro
2010-04-04T14:19:29Z

> On Fri, Apr 02, 2010 at 05:14:38PM +0800, KOSAKI Motohiro wrote:
> > > > > This patch makes a lot of sense than previous. however I think <1% anon ratio
> > > > > shouldn't happen anyway because file lru doesn't have reclaimable pages.
> > > > > <1% seems no good reclaim rate.
> > > >
> > > > Oops, the above mention is wrong. sorry. only 1 page is still too big.
> > > > because under streaming io workload, the number of scanning anon pages should
> > > > be zero. this is very strong requirement. if not, backup operation will makes
> > > > a lot of swapping out.
> > > Sounds there is no big impact for the workload which you mentioned with the patch.
> > > please see below descriptions.
> > > I updated the description of the patch as fengguang suggested.
> >
> > Umm.. sorry, no.
> >
> > "one fix but introduce another one bug" is not good deal. instead,
> > I'll revert the guilty commit at first as akpm mentioned.
> Even we revert the commit, the patch still has its benefit, as it increases
> calculation precision, right?

no, you shouldn't ignore the regression case.

If we can remove the streaming io corner case by another patch, this patch
can be considered to merge.

thanks.