Re: [PATCH 01/27] mm, vmstat: Add infrastructure for per-node vmstats

Mel Gorman
2016-06-10T13:47:52Z

On Fri, Jun 10, 2016 at 03:31:41PM +0200, Vlastimil Babka wrote:
> On 06/09/2016 08:04 PM, Mel Gorman wrote:
> > References: bnc#969297 PM performance -- intel_pstate
> > Patch-mainline: No, expected 4.7 and queued in linux-mm
> > Patch-name: patches.suse/mm-vmstat-Add-infrastructure-for-per-node-vmstats.patch
>
> Remove?
>

Yes. Clearly I fat-fingers a cherry pick and used the wrong command that
added distro-specific metadata. Sorry.

> > VM statistic counters for reclaim decisions are zone-based. If the kernel
> > is to reclaim on a per-node basis then we need to track per-node statistics
> > but there is no infrastructure for that. The most notable change is that
> > the old node_page_state is renamed to sum_zone_node_page_state. The new
> > node_page_state takes a pglist_data and uses per-node stats but none exist
> > yet. There is some renaming such as vm_stat to vm_zone_stat and the addition
> > of vm_node_stat and the renaming of mod_state to mod_zone_state. Otherwise,
> > this is mostly a mechanical patch with no functional change. There is a
> > lot of similarity between the node and zone helpers which is unfortunate
> > but there was no obvious way of reusing the code and maintaining type safety.
> >
> > Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> > Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> > Signed-off-by: Mel Gorman <mgorman@suse.com>
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>
> Some nitpicks below.
>
> > @@ -237,12 +286,26 @@ static inline void __inc_zone_page_state(struct page *page,
> > __inc_zone_state(page_zone(page), item);
> > }
> >
> > +static inline void __inc_node_page_state(struct page *page,
> > + enum node_stat_item item)
> > +{
> > + __inc_node_state(page_zone(page)->zone_pgdat, item);
>
> This page -> node translation looks needlessly ineffective. How about
> using NODE_DATA(page_to_nid(page)).
>

Yes, I will. I won't answer the individual feedbacks. They all seem
reasonable.

--
Mel Gorman
SUSE Labs