Re: ZVC/zone_reclaim: Leave 1% of unmapped pagecache pages for file I/O

Andrew Morton
2006-06-30T23:38:49Z

Christoph Lameter <clameter@sgi.com> wrote:
>
> +min_unmapped:
> +
> +A percentage of the file backed pages in each zone. Zone reclaim will only
> +occur if more than this percentage of pages are file backed and unmapped.
> +This is to insure that a minimal amount of local pages is still available
> +for file I/O even if the node is overallocated.
> +
> +The default is 1 percent.
> +

Probably this should have a big "NUMA only" slapped on it so people don't
wonder why they don't have such a file.

Also, it's nice if the naming of these control files can communicate the
units to the operator. In the case of /proc/sys/vm we use _ratio to
indicate that it's a proportional control in the 0% - 100% range.

So /proc/sys/vm/min_unmapped_ratio would be clearer, and more consistent.

<looks forward to the day when this becomes per-node :(>