Re: [PATCH]vmscan: handle underflow for get_scan_ratio

KOSAKI Motohiro
2010-04-13T01:30:38Z

> On 04/09/2010 05:20 PM, Andrew Morton wrote:
>
> > Come to that, it's not obvious that we need this in 2.6.34 either. What
> > is the user-visible impact here?
>
> I suspect very little impact, especially during workloads
> where we can just reclaim clean page cache at DEF_PRIORITY.
> FWIW, the patch looks good to me, so:
>
> Acked-by: Rik van Riel <riel@redhat.com>
>

I'm surprised this ack a bit. Rik, do you have any improvement plan about
streaming io detection logic?
I think the patch have a slightly marginal benefit, it help to <1% scan
ratio case. but it have big regression, it cause streaming io (e.g. backup
operation) makes tons swap.

So, I thought we sould do either,
1) drop this one
2) merge to change stream io detection logic improvement at first, and
merge this one at second.

Am i missing something?