|From:||Vincent Guittot <email@example.com>|
|To:||firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org|
|Subject:||[PATCH v2 00/11] sched: consolidation of cpu_power|
|Date:||Fri, 23 May 2014 17:52:54 +0200|
|Cc:||email@example.com, Morten.Rasmussen@arm.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, Vincent Guittot <firstname.lastname@example.org>|
Part of this patchset was previously part of the larger tasks packing patchset . I have splitted the latter in 3 different patchsets (at least) to make the thing easier. -configuration of sched_domain topology  -update and consolidation of cpu_power (this patchset) -tasks packing algorithm SMT system is no more the only system that can have a CPUs with an original capacity that is different from the default value. We need to extend the use of cpu_power_orig to all kind of platform so the scheduler will have both the maximum capacity (cpu_power_orig/power_orig) and the current capacity (cpu_power/power) of CPUs and sched_groups. A new function arch_scale_cpu_power has been created and replace arch_scale_smt_power, which is SMT specifc in the computation of the capapcity of a CPU. During load balance, the scheduler evaluates the number of tasks that a group of CPUs can handle. The current method assumes that tasks have a fix load of SCHED_LOAD_SCALE and CPUs have a default capacity of SCHED_POWER_SCALE. This assumption generates wrong decision by creating ghost cores and by removing real ones when the original capacity of CPUs is different from the default SCHED_POWER_SCALE. Now that we have the original capacity of a CPUS and its activity/utilization, we can evaluate more accuratly the capacity of a group of CPUs. This patchset mainly replaces the old capacity method by a new one and has kept the policy almost unchanged whereas we can certainly take advantage of this new statistic in several other places of the load balance. TODO: - align variable's and field's name with the renaming  Tests results: I have put below results of 2 tests: - hackbench -l 500 -s 4096 - scp of 100MB file on the platform on a dual cortex-A7 hackbench scp tip/master 25.75s(+/-0.25) 5.16MB/s(+/-1.49) + patches 1,2 25.89s(+/-0.31) 5.18MB/s(+/-1.45) + patches 3-10 25.68s(+/-0.22) 7.00MB/s(+/-1.88) + irq accounting 25.80s(+/-0.25) 8.06MB/s(+/-0.05) on a quad cortex-A15 hackbench scp tip/master 15.69s(+/-0.16) 9.70MB/s(+/-0.04) + patches 1,2 15.53s(+/-0.13) 9.72MB/s(+/-0.05) + patches 3-10 15.56s(+/-0.22) 9.88MB/s(+/-0.05) + irq accounting 15.99s(+/-0.08) 10.37MB/s(+/-0.03) The improvement of scp bandwidth happens when tasks and irq are using different CPU which is a bit random without irq accounting config Change since V1: - add 3 fixes - correct some commit messages - replace capacity computation by activity - take into account current cpu capacity  https://lkml.org/lkml/2013/10/18/121  https://lkml.org/lkml/2014/3/19/377  https://lkml.org/lkml/2014/5/14/622 Vincent Guittot (11): sched: fix imbalance flag reset sched: remove a wake_affine condition sched: fix avg_load computation sched: Allow all archs to set the power_orig ARM: topology: use new cpu_power interface sched: add per rq cpu_power_orig Revert "sched: Put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED" sched: get CPU's activity statistic sched: test the cpu's capacity in wake affine sched: move cfs task on a CPU with higher capacity sched: replace capacity by activity arch/arm/kernel/topology.c | 4 +- kernel/sched/core.c | 2 +- kernel/sched/fair.c | 229 ++++++++++++++++++++++----------------------- kernel/sched/sched.h | 5 +- 4 files changed, 118 insertions(+), 122 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to email@example.com More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Copyright © 2014, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds