linux-kernel - Re: [PATCH 19/27] mm: Move vmscan writes and file write accounting to the node

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Date:	Thu, 23 Jun 2016 14:57:58 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>, Rik van Riel <riel@...riel.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 19/27] mm: Move vmscan writes and file write accounting
 to the node

On Wed, Jun 22, 2016 at 04:40:39PM +0200, Michal Hocko wrote:
> On Tue 21-06-16 15:15:58, Mel Gorman wrote:
> > As reclaim is now node-based, it follows that page write activity
> > due to page reclaim should also be accounted for on the node. For
> > consistency, also account page writes and page dirtying on a per-node
> > basis.
> > 
> > After this patch, there are a few remaining zone counters that may
> > appear strange but are fine. NUMA stats are still per-zone as this is a
> > user-space interface that tools consume. NR_MLOCK, NR_SLAB_*, NR_PAGETABLE,
> > NR_KERNEL_STACK and NR_BOUNCE are all allocations that potentially pin
> > low memory and cannot trivially be reclaimed on demand. This information
> > is still useful for debugging a page allocation failure warning.
> 
> As I've said in other patch. I think we will need to provide
> /proc/nodeinfo to fill the gap.
> 

I added a patch on top that prints the node stats in zoneinfo but only
once for the first populated zone in a node. Doing this or creating a
new file are both potentially surprising but extending zoneinfo means
there is a greater chance that a user will spot the change.

-- 
Mel Gorman
SUSE Labs