[Qemu-devel] Re: [RFC][PATCH 1/3] Linux/Guest unmapped page cache control

[Christoph Lameter]

On Fri, 29 Oct 2010, Balbir Singh wrote:

> A lot of the code is borrowed from zone_reclaim_mode logic for
> __zone_reclaim(). One might argue that the with ballooning and
> KSM this feature is not very useful, but even with ballooning,

Interesting use of zone reclaim. I am having a difficult time reviewing
the patch since you move and modify functions at the same time. Could you
separate that out a bit?

> +#define UNMAPPED_PAGE_RATIO 16

Maybe come up with a scheme that allows better configuration of the
mininum? I think in some setting we may want an absolute limit and in
other a fraction of something (total zone size or working set?)


> +bool should_balance_unmapped_pages(struct zone *zone)
> +{
> +     if (unmapped_page_control &&
> +             (zone_unmapped_file_pages(zone) >
> +                     UNMAPPED_PAGE_RATIO * zone->min_unmapped_pages))
> +             return true;
> +     return false;
> +}