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Subject[tip:sched/core] sched: Tweak sched_latency and min_granularity
Commit-ID:  21406928afe43f1db6acab4931bb8c886f4d04ce
Gitweb: http://git.kernel.org/tip/21406928afe43f1db6acab4931bb8c886f4d04ce
Author: Mike Galbraith <efault@gmx.de>
AuthorDate: Thu, 11 Mar 2010 17:17:15 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 11 Mar 2010 18:32:51 +0100

sched: Tweak sched_latency and min_granularity

Allow LAST_BUDDY to kick in sooner, improving cache utilization as soon as
a second buddy pair arrives on scene. The cost is latency starting to climb
sooner, the tbenefit for tbench 8 on my Q6600 box is ~2%. No detrimental
effects noted in normal idesktop usage.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301285.6785.34.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched_fair.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 69e5820..d19df5b 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -35,8 +35,8 @@
* (to see the precise effective timeslice length of your workload,
* run vmstat and monitor the context-switches (cs) field)
*/
-unsigned int sysctl_sched_latency = 5000000ULL;
-unsigned int normalized_sysctl_sched_latency = 5000000ULL;
+unsigned int sysctl_sched_latency = 6000000ULL;
+unsigned int normalized_sysctl_sched_latency = 6000000ULL;

/*
* The initial- and re-scaling of tunables is configurable
@@ -52,15 +52,15 @@ enum sched_tunable_scaling sysctl_sched_tunable_scaling

/*
* Minimal preemption granularity for CPU-bound tasks:
- * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ * (default: 2 msec * (1 + ilog(ncpus)), units: nanoseconds)
*/
-unsigned int sysctl_sched_min_granularity = 1000000ULL;
-unsigned int normalized_sysctl_sched_min_granularity = 1000000ULL;
+unsigned int sysctl_sched_min_granularity = 2000000ULL;
+unsigned int normalized_sysctl_sched_min_granularity = 2000000ULL;

/*
* is kept at sysctl_sched_latency / sysctl_sched_min_granularity
*/
-static unsigned int sched_nr_latency = 5;
+static unsigned int sched_nr_latency = 3;

/*
* After fork, child runs first. If set to 0 (default) then

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