Add SD_BALANCE_NEWIDLE flag at MC level and CPU level
if sched_mc is set. This helps power savings and
will not affect performance when sched_mc=0
Ingo and Mike Galbraith have optimised the SD flags by
removing SD_BALANCE_NEWIDLE at MC and CPU level. This
helps performance but hurts power savings since this
slows down task consolidation by reducing the number
of times load_balance is run.
sched: fine-tune SD_MC_INIT
commit 14800984706bf6936bbec5187f736e928be5c218
Author: Mike Galbraith <efault@gmx.de>
Date: Fri Nov 7 15:26:50 2008 +0100
sched: re-tune balancing -- revert
commit 9fcd18c9e63e325dbd2b4c726623f760788d5aa8
Author: Ingo Molnar <mingo@elte.hu>
Date: Wed Nov 5 16:52:08 2008 +0100
This patch selectively enables SD_BALANCE_NEWIDLE flag
only when sched_mc is set to 1 or 2. This helps power savings
by task consolidation and also does not hurt performance at
sched_mc=0 where all power saving optimisations are turned off.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
---
include/linux/sched.h | 13 +++++++++++++
include/linux/topology.h | 6 ++++--
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5fe906b..07348ff 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -793,6 +793,19 @@ static inline int sd_balance_for_package_power(void)
return 0;
}
+/*
+ * Optimise SD flags for power savings:
+ * SD_BALANCE_NEWIDLE helps agressive task consolidation and power savings.
+ * Keep default SD flags if sched_{smt,mc}_power_saving=0
+ */
+
+static inline int sd_power_saving_flags(void)
+{
+ if (sched_mc_power_savings | sched_smt_power_savings)
+ return SD_BALANCE_NEWIDLE;
+
+ return 0;
+}
struct sched_group {
struct sched_group *next; /* Must be a circular list */
diff --git a/include/linux/topology.h b/include/linux/topology.h
index 7f10439..1628b43 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -125,7 +125,8 @@ void arch_update_cpu_topology(void);
| SD_WAKE_AFFINE \
| SD_WAKE_BALANCE \
| SD_SHARE_PKG_RESOURCES\
- | sd_balance_for_mc_power(),\
+ | sd_balance_for_mc_power()\
+ | sd_power_saving_flags(),\
.last_balance = jiffies, \
.balance_interval = 1, \
}
@@ -150,7 +151,8 @@ void arch_update_cpu_topology(void);
| SD_BALANCE_FORK \
| SD_WAKE_AFFINE \
| SD_WAKE_BALANCE \
- | sd_balance_for_package_power(),\
+ | sd_balance_for_package_power()\
+ | sd_power_saving_flags(),\
.last_balance = jiffies, \
.balance_interval = 1, \
}
--
