From 100fdaee70ebf5f31b9451fbc01300c627091328 Mon Sep 17 00:00:00 2001 From: Vaidyanathan Srinivasan Date: Thu, 18 Dec 2008 23:26:47 +0530 Subject: [PATCH] sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0 Impact: change task balancing to save power more agressively 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 Date: Fri Nov 7 15:26:50 2008 +0100 sched: re-tune balancing -- revert commit 9fcd18c9e63e325dbd2b4c726623f760788d5aa8 Author: Ingo Molnar 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 Acked-by: Balbir Singh Acked-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- 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 a96726658ec..5a933d92547 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -792,6 +792,19 @@ 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 0ce7c0dac06..e632d29f054 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -125,7 +125,8 @@ int 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 @@ int 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, \ } -- 2.39.5