From 724d562ae08905854c2940994950b68c2939db78 Mon Sep 17 00:00:00 2001 From: Patrick Bellasi Date: Mon, 22 Jun 2015 18:11:44 +0100 Subject: [PATCH] sched/tune: add sysctl interface to define a boost value The current (CFS) scheduler implementation does not allow "to boost" tasks performance by running them at a higher OPP compared to the minimum required to meet their workload demands. To support tasks performance boosting the scheduler should provide a "knob" which allows to tune how much the system is going to be optimised for energy efficiency vs performance. This patch is the first of a series which provides a simple interface to define a tuning knob. One system-wide "boost" tunable is exposed via: /proc/sys/kernel/sched_cfs_boost which can be configured in the range [0..100], to define a percentage where: - 0% boost requires to operate in "standard" mode by scheduling tasks at the minimum capacities required by the workload demand - 100% boost requires to push at maximum the task performances, "regardless" of the incurred energy consumption A boost value in between these two boundaries is used to bias the power/performance trade-off, the higher the boost value the more the scheduler is biased toward performance boosting instead of energy efficiency. cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Patrick Bellasi --- include/linux/sched/sysctl.h | 16 ++++++++++++++++ init/Kconfig | 26 ++++++++++++++++++++++++++ kernel/sched/Makefile | 1 + kernel/sched/tune.c | 16 ++++++++++++++++ kernel/sysctl.c | 11 +++++++++++ 5 files changed, 70 insertions(+) create mode 100644 kernel/sched/tune.c diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h index c9e4731cf10b..4479e48c7712 100644 --- a/include/linux/sched/sysctl.h +++ b/include/linux/sched/sysctl.h @@ -77,6 +77,22 @@ extern int sysctl_sched_rt_runtime; extern unsigned int sysctl_sched_cfs_bandwidth_slice; #endif +#ifdef CONFIG_SCHED_TUNE +extern unsigned int sysctl_sched_cfs_boost; +int sysctl_sched_cfs_boost_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *length, + loff_t *ppos); +static inline unsigned int get_sysctl_sched_cfs_boost(void) +{ + return sysctl_sched_cfs_boost; +} +#else +static inline unsigned int get_sysctl_sched_cfs_boost(void) +{ + return 0; +} +#endif + #ifdef CONFIG_SCHED_AUTOGROUP extern unsigned int sysctl_sched_autogroup_enabled; #endif diff --git a/init/Kconfig b/init/Kconfig index e1d1d6936f92..ee1dd90254b7 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1237,6 +1237,32 @@ config SCHED_AUTOGROUP desktop applications. Task group autogeneration is currently based upon task session. +config SCHED_TUNE + bool "Boosting for CFS tasks (EXPERIMENTAL)" + help + This option enables the system-wide support for task boosting. + When this support is enabled a new sysctl interface is exposed to + userspace via: + /proc/sys/kernel/sched_cfs_boost + which allows to set a system-wide boost value in range [0..100]. + + The currently boosting strategy is implemented in such a way that: + - a 0% boost value requires to operate in "standard" mode by + scheduling all tasks at the minimum capacities required by their + workload demand + - a 100% boost value requires to push at maximum the task + performances, "regardless" of the incurred energy consumption + + A boost value in between these two boundaries is used to bias the + power/performance trade-off, the higher the boost value the more the + scheduler is biased toward performance boosting instead of energy + efficiency. + + Since this support exposes a single system-wide knob, the specified + boost value is applied to all (CFS) tasks in the system. + + If unsure, say N. + config SYSFS_DEPRECATED bool "Enable deprecated sysfs features to support old userspace tools" depends on SYSFS diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile index 0eabc9db4c3d..c6a85f813dfd 100644 --- a/kernel/sched/Makefile +++ b/kernel/sched/Makefile @@ -18,5 +18,6 @@ obj-$(CONFIG_SMP) += cpupri.o cpudeadline.o obj-$(CONFIG_SCHED_AUTOGROUP) += auto_group.o obj-$(CONFIG_SCHEDSTATS) += stats.o obj-$(CONFIG_SCHED_DEBUG) += debug.o +obj-$(CONFIG_SCHED_TUNE) += tune.o obj-$(CONFIG_CGROUP_CPUACCT) += cpuacct.o obj-$(CONFIG_CPU_FREQ_GOV_SCHED) += cpufreq_sched.o diff --git a/kernel/sched/tune.c b/kernel/sched/tune.c new file mode 100644 index 000000000000..a93af9c2f267 --- /dev/null +++ b/kernel/sched/tune.c @@ -0,0 +1,16 @@ +#include "sched.h" + +unsigned int sysctl_sched_cfs_boost __read_mostly; + +int +sysctl_sched_cfs_boost_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + + if (ret || !write) + return ret; + + return 0; +} diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 11783ed47dd3..2cf1f8610ded 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -435,6 +435,17 @@ static struct ctl_table kern_table[] = { .extra1 = &one, }, #endif +#ifdef CONFIG_SCHED_TUNE + { + .procname = "sched_cfs_boost", + .data = &sysctl_sched_cfs_boost, + .maxlen = sizeof(sysctl_sched_cfs_boost), + .mode = 0644, + .proc_handler = &sysctl_sched_cfs_boost_handler, + .extra1 = &zero, + .extra2 = &one_hundred, + }, +#endif #ifdef CONFIG_PROVE_LOCKING { .procname = "prove_locking", -- 2.34.1