Re: [PATCH] on memoryless node, /proc/pagetypeinfo is displayed slightly funny output. take2

From: Mel Gorman
Date: Tue Apr 29 2008 - 06:44:00 EST


On (29/04/08 17:17), KOSAKI Motohiro didst pronounce:
> > > Index: b/mm/vmstat.c
> > > ===================================================================
> > > --- a/mm/vmstat.c 2008-04-29 16:48:58.000000000 +0900
> > > +++ b/mm/vmstat.c 2008-04-29 16:58:33.000000000 +0900
> > > @@ -638,6 +638,10 @@ static int pagetypeinfo_show(struct seq_
> > > {
> > > pg_data_t *pgdat = (pg_data_t *)arg;
> > >
> > > + /* check memoryless ndoe*/
> >
> > ndoe -> node ?
>
> Agghhh!
> you are right ;-)
>
> fixed version is here.
>

I see what you mean. The headers for a node with no populated zones looks
a bit odd. I was briefly thrown by the check for N_HIGH_MEMORY wondering
why it was not a check for N_NORMAL_MEMORY. A double-check showed that
N_NORMAL_MEMORY only has meaning on CONFIG_HIGHMEM machines and a check for
"any memory on the node" should use N_HIGH_MEMORY which is what you do.

So, your patch looks correct but unfortunately it is whitespace-damaged
and would not apply as-is. I included a whitespace-fixed version below for
convenience with a slightly clearer leader which I have acked.

Thanks

==========
On memoryless node, /proc/pagetypeinfo outputs headers for nodes with no
populated zones. This is confusing as shown in the following example.

>>>
Page block order: 14
Pages per block: 16384

Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
Page block order: 14
Pages per block: 16384

Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
<SNIP>
<<<

Note the headers with no zone information. This patch checks if the node
has any memory before outputting anything.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Mel Gorman <mel@xxxxxxxxx>
---
mm/vmstat.c | 4 ++++
1 file changed, 4 insertions(+)

Index: b/mm/vmstat.c
===================================================================
--- a/mm/vmstat.c 2008-04-29 16:48:58.000000000 +0900
+++ b/mm/vmstat.c 2008-04-29 16:58:33.000000000 +0900
@@ -638,6 +638,10 @@ static int pagetypeinfo_show(struct seq_
{
pg_data_t *pgdat = (pg_data_t *)arg;

+ /* check memoryless node */
+ if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
+ return 0;
+
seq_printf(m, "Page block order: %d\n", pageblock_order);
seq_printf(m, "Pages per block: %lu\n", pageblock_nr_pages);
seq_putc(m, '\n');

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