Messages in this thread Patch in this message | | | From | Vaidyanathan Srinivasan <> | Subject | [PATCH v6 6/7] sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0 | Date | Wed, 17 Dec 2008 22:57:38 +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 | 10 ++++++++++ include/linux/topology.h | 6 ++++-- 2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index 888f2b2..e894892 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -782,6 +782,16 @@ enum powersavings_balance_level { ((sched_mc_power_savings || sched_smt_power_savings) ? \ SD_POWERSAVINGS_BALANCE : 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 + */ + +#define POWERSAVING_SD_FLAGS \ + ((sched_mc_power_savings || sched_smt_power_savings) ? \ + SD_BALANCE_NEWIDLE : 0) + #define test_sd_parent(sd, flag) ((sd->parent && \ (sd->parent->flags & flag)) ? 1 : 0) diff --git a/include/linux/topology.h b/include/linux/topology.h index 117f1b7..26c608c 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\ - | BALANCE_FOR_MC_POWER, \ + | BALANCE_FOR_MC_POWER \ + | POWERSAVING_SD_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 \ - | BALANCE_FOR_PKG_POWER,\ + | BALANCE_FOR_PKG_POWER \ + | POWERSAVING_SD_FLAGS, \ .last_balance = jiffies, \ .balance_interval = 1, \ }
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