linux-kernel - Re: [PATCH mmotm] Fix NUMA accounting in numastat.txt

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Message-Id: <20090901162937.431a844c.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Tue, 1 Sep 2009 16:29:37 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	lkml <linux-kernel@...r.kernel.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	cl@...ux-foundation.org
Subject: Re: [PATCH mmotm] Fix NUMA accounting in numastat.txt

On Tue, 1 Sep 2009 16:24:19 +0900
Minchan Kim <minchan.kim@...il.com> wrote:

> Hi, Kame.
> 
> On Tue, 1 Sep 2009 16:17:21 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:
> 
> > On Tue, 1 Sep 2009 13:53:21 +0900
> > Minchan Kim <minchan.kim@...il.com> wrote:
> > 
> > > 
> > > In Documentation/numastat.txt, it confused me.
> > > For example, there are nodes [0,1] in system.
> > > 
> > > barrios:~$ cat /proc/zoneinfo | egrep 'numa|zone'
> > > Node 0, zone	DMA
> > > 	numa_hit	33226
> > > 	numa_miss	1739
> > > 	numa_foreign	27978
> > > 	..
> > > 	..
> > > Node 1, zone	DMA
> > > 	numa_hit	307
> > > 	numa_miss	46900
> > > 	numa_foreign	0
> > > 
> > > 1) In node 0,  NUMA_MISS means it wanted to allocate page
> > > in node 1 but ended up with page in node 0
> > > 
> > > 2) In node 0, NUMA_FOREIGN means it wanted to allocate page
> > > in node 0 but ended up with page from Node 1.
> > > 
> > > But now, numastat explains it oppositely about (MISS, FOREIGN).
> > > Let's fix up with viewpoint of zone. 
> > > 
> > 
> > I'm confused....documentation is really bad ?
> > Implementation isn't ?
> 
> At that time, I though of it. 
> But I knew code is right since zone_stat_item said follwing as. 
> NUMA_MISS is rather unclear but NUMA_FOREIGN is clear, I think.
> 
>         NUMA_MISS,              /* allocated in non intended node */
>         NUMA_FOREIGN,           /* was intended here, hit elsewhere */
>
Ah, ok, it comments are correct your patch makes sense.
 
> Also I am worry about legacy tools related to NUMA but I don't know it.
> Code change will break them.
Ah, hmm. maybe.

Thanks. Add Christoph to CC:, maybe he can Ack.

Thanks,
-Kame




> > Hmm, this function ?
> > ==
> > void zone_statistics(struct zone *preferred_zone, struct zone *z)
> > {
> >         if (z->zone_pgdat == preferred_zone->zone_pgdat) {
> >                 __inc_zone_state(z, NUMA_HIT);
> >         } else {
> >                 __inc_zone_state(z, NUMA_MISS);
> >                 __inc_zone_state(preferred_zone, NUMA_FOREIGN);
> >         }
> >         if (z->node == numa_node_id())
> >                 __inc_zone_state(z, NUMA_LOCAL);
> >         else
> >                 __inc_zone_state(z, NUMA_OTHER);
> > }
> > ==
> > 
> > 
> > > Signed-off-by: Minchan Kim <minchan.kim@...il.com>
> > > ---
> > >  Documentation/numastat.txt |    8 ++++----
> > >  1 files changed, 4 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/Documentation/numastat.txt b/Documentation/numastat.txt
> > > index 80133ac..9fcc9a6 100644
> > > --- a/Documentation/numastat.txt
> > > +++ b/Documentation/numastat.txt
> > > @@ -7,10 +7,10 @@ All units are pages. Hugepages have separate counters.
> > > 
> > >  numa_hit			A process wanted to allocate memory from this node,
> > >  					and succeeded.
> > > -numa_miss			A process wanted to allocate memory from this node,
> > > -					but ended up with memory from another.
> > > -numa_foreign		A process wanted to allocate on another node,
> > > -				    but ended up with memory from this one.
> > > +numa_miss			A process wanted to allocate memory from another node,
> > > +					but ended up with memory from this node.
> > > +numa_foreign		A process wanted to allocate on this node,
> > > +				    but ended up with memory from another one.
> > >  local_node			A process ran on this node and got memory from it.
> > >  other_node			A process ran on this node and got memory from another node.
> > >  interleave_hit 		Interleaving wanted to allocate from this node
> > > --
> > > 1.5.4.3
> > > 
> > > 
> > > 
> > > -- 
> > > Kind regards,
> > > Minchan Kim
> > > 
> > > --
> > > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > > the body to majordomo@...ck.org.  For more info on Linux MM,
> > > see: http://www.linux-mm.org/ .
> > > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
> > > 
> > 
> 
> 
> -- 
> Kind regards,
> Minchan Kim
> 

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