Re: [PATCH 1/4] numa,x86: store maximum numa node distance

From: Rik van Riel
Date: Fri May 09 2014 - 11:11:36 EST


On 05/09/2014 05:45 AM, Peter Zijlstra wrote:
On Thu, May 08, 2014 at 01:23:28PM -0400, riel@xxxxxxxxxx wrote:
From: Rik van Riel <riel@xxxxxxxxxx>

Store the maximum node distance, so the numa placement code can do
better placement on systems with complex numa topology.

The function max_node_distance will return LOCAL_DISTANCE if the
system has simple NUMA topology, with only a single level of
remote distance.

Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Tested-by: Chegu Vinod <chegu_vinod@xxxxxx>
---
arch/x86/include/asm/topology.h | 3 +++
arch/x86/mm/numa.c | 25 +++++++++++++++++++++++++
include/linux/topology.h | 3 +++
3 files changed, 31 insertions(+)


Why are you doing this in arch code? I would've expected some extra code
to sched_init_numa() which is generic code that analyses the distance
table and reconstructs the actual topology from it.

The only reason it is in the arch code is that node_distance()
is in arch code today.

If there is no good reason for node_distance and the node
distances array to be in arch code, I could take a stab at
making it generic...

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