Commit-ID: 10717dcde10d09f9fcee53a12a4236af1a82b484
Gitweb: http://git.kernel.org/tip/10717dcde10d09f9fcee53a12a4236af1a82b484
Author: Alex Shi <alex.shi@xxxxxxxxx>
AuthorDate: Wed, 6 Jun 2012 14:52:51 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 6 Jun 2012 16:52:25 +0200
sched/numa: Load balance between remote nodes
Commit cb83b629b ("sched/numa: Rewrite the CONFIG_NUMA sched
domain support") removed the NODE sched domain and started checking
if the node distance in SLIT table is farther than REMOTE_DISTANCE,
if so, it will lose the load balance chance at exec/fork/wake_affine
points.
But actually, even the node distance is farther than REMOTE_DISTANCE.
Modern CPUs also has QPI like connections, which ensures that memory
access is not too slow between nodes. So the above change in behavior
on NUMA machine causes a performance regression on various benchmarks:
hackbench, tbench, netperf, oltp, etc.
This patch will recover the scheduler behavior to old mode on all my
Intel platforms: NHM EP/EX, WSM EP, SNB EP/EP4S, and thus fixes the
perfromance regressions. (all of them just have 2 kinds distance, 10, 21)
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1338965571-9812-1-git-send-email-alex.shi@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/core.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c46958e..6546083 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6321,7 +6321,7 @@ static int sched_domains_curr_level;
static inline int sd_local_flags(int level)
{
- if (sched_domains_numa_distance[level] > REMOTE_DISTANCE)
+ if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE)
return 0;
return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE;
--
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