diff options
| author | Anton Blanchard <anton@samba.org> | 2010-05-17 00:19:56 +0400 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2010-05-21 11:31:12 +0400 |
| commit | 56608209d34b8add40af54031d4e420afbcde9f6 (patch) | |
| tree | 6aa984dc088df39b426f6320f3cbd09c26e5e72e /arch | |
| parent | b878dc00595440586874952dd85ce9b803360b87 (diff) | |
| download | linux-56608209d34b8add40af54031d4e420afbcde9f6.tar.xz | |
powerpc/numa: Set a smaller value for RECLAIM_DISTANCE to enable zone reclaim
I noticed /proc/sys/vm/zone_reclaim_mode was 0 on a ppc64 NUMA box. It gets
enabled via this:
/*
* If another node is sufficiently far away then it is better
* to reclaim pages in a zone before going off node.
*/
if (distance > RECLAIM_DISTANCE)
zone_reclaim_mode = 1;
Since we use the default value of 20 for REMOTE_DISTANCE and 20 for
RECLAIM_DISTANCE it never kicks in.
The local to remote bandwidth ratios can be quite large on System p
machines so it makes sense for us to reclaim clean pagecache locally before
going off node.
The patch below sets a smaller value for RECLAIM_DISTANCE and thus enables
zone reclaim.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/include/asm/topology.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h index 84ad11f65dc2..32adf7280720 100644 --- a/arch/powerpc/include/asm/topology.h +++ b/arch/powerpc/include/asm/topology.h @@ -18,6 +18,16 @@ struct device_node; */ #define RECLAIM_DISTANCE 10 +/* + * Before going off node we want the VM to try and reclaim from the local + * node. It does this if the remote distance is larger than RECLAIM_DISTANCE. + * With the default REMOTE_DISTANCE of 20 and the default RECLAIM_DISTANCE of + * 20, we never reclaim and go off node straight away. + * + * To fix this we choose a smaller value of RECLAIM_DISTANCE. + */ +#define RECLAIM_DISTANCE 10 + #include <asm/mmzone.h> static inline int cpu_to_node(int cpu) |