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

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Date:	Fri, 10 Jun 2016 14:47:47 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>, Rik van Riel <riel@...riel.com>,
	Johannes Weiner <hannes@...xchg.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/27] mm, vmstat: Add infrastructure for per-node vmstats

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@...hsingularity.net>
> > Acked-by: Johannes Weiner <hannes@...xchg.org>
> > Signed-off-by: Mel Gorman <mgorman@...e.com>
> 
> Acked-by: Vlastimil Babka <vbabka@...e.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