Messages in this thread Patch in this message | | | From | Vaidyanathan Srinivasan <> | Subject | [PATCH v7 7/8] sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0 | Date | Thu, 18 Dec 2008 23:26:47 +0530 |
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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, \ }
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