sched: reintroduce SMP tunings again

Yanmin Zhang reported an aim7 regression and bisected it down to:

 |  commit 38ad464d410dadceda1563f36bdb0be7fe4c8938
 |  Author: Ingo Molnar <mingo@elte.hu>
 |  Date:   Mon Oct 15 17:00:02 2007 +0200
 |
 |     sched: uniform tunings
 |
 |     use the same defaults on both UP and SMP.

fix this by reintroducing similar SMP tunings again. This resolves
the regression.

(also update the comments to match the ilog2(nr_cpus) tuning effect)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 9 insertions, 9 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c495dcf7031b..7264814ba62a 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -22,7 +22,7 @@
 
 /*
  * Targeted preemption latency for CPU-bound tasks:
- * (default: 20ms, units: nanoseconds)
+ * (default: 20ms * ilog(ncpus), units: nanoseconds)
  *
  * NOTE: this latency value is not the same as the concept of
  * 'timeslice length' - timeslices in CFS are of variable length
@@ -32,18 +32,18 @@
  * (to see the precise effective timeslice length of your workload,
  *  run vmstat and monitor the context-switches (cs) field)
  */
-const_debug unsigned int sysctl_sched_latency = 20000000ULL;
+unsigned int sysctl_sched_latency = 20000000ULL;
 
 /*
  * Minimal preemption granularity for CPU-bound tasks:
- * (default: 1 msec, units: nanoseconds)
+ * (default: 1 msec * ilog(ncpus), units: nanoseconds)
  */
-const_debug unsigned int sysctl_sched_min_granularity = 1000000ULL;
+unsigned int sysctl_sched_min_granularity = 1000000ULL;
 
 /*
  * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
  */
-const_debug unsigned int sched_nr_latency = 20;
+unsigned int sched_nr_latency = 20;
 
 /*
  * After fork, child runs first. (default) If set to 0 then
@@ -61,23 +61,23 @@ unsigned int __read_mostly sysctl_sched_compat_yield;
 
 /*
  * SCHED_BATCH wake-up granularity.
- * (default: 10 msec, units: nanoseconds)
+ * (default: 10 msec * ilog(ncpus), units: nanoseconds)
  *
  * This option delays the preemption effects of decoupled workloads
  * and reduces their over-scheduling. Synchronous workloads will still
  * have immediate wakeup/sleep latencies.
  */
-const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL;
+unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL;
 
 /*
  * SCHED_OTHER wake-up granularity.
- * (default: 10 msec, units: nanoseconds)
+ * (default: 10 msec * ilog(ncpus), units: nanoseconds)
  *
  * This option delays the preemption effects of decoupled workloads
  * and reduces their over-scheduling. Synchronous workloads will still
  * have immediate wakeup/sleep latencies.
  */
-const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL;
+unsigned int sysctl_sched_wakeup_granularity = 10000000UL;
 
 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;