Merge tag 'for-5.3/block-20190708' of git://git.kernel.dk/linux-block

[linux.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index a41d8fbe09d81d7d79812bcfc6a0cb0bf4abc62b..d3a1df424ce48411c29141c61e612eadb3a25211 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -677,6 +677,59 @@ config HAVE_UNSTABLE_SCHED_CLOCK
 config GENERIC_SCHED_CLOCK
        bool
 
+menu "Scheduler features"
+
+config UCLAMP_TASK
+       bool "Enable utilization clamping for RT/FAIR tasks"
+       depends on CPU_FREQ_GOV_SCHEDUTIL
+       help
+         This feature enables the scheduler to track the clamped utilization
+         of each CPU based on RUNNABLE tasks scheduled on that CPU.
+
+         With this option, the user can specify the min and max CPU
+         utilization allowed for RUNNABLE tasks. The max utilization defines
+         the maximum frequency a task should use while the min utilization
+         defines the minimum frequency it should use.
+
+         Both min and max utilization clamp values are hints to the scheduler,
+         aiming at improving its frequency selection policy, but they do not
+         enforce or grant any specific bandwidth for tasks.
+
+         If in doubt, say N.
+
+config UCLAMP_BUCKETS_COUNT
+       int "Number of supported utilization clamp buckets"
+       range 5 20
+       default 5
+       depends on UCLAMP_TASK
+       help
+         Defines the number of clamp buckets to use. The range of each bucket
+         will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
+         number of clamp buckets the finer their granularity and the higher
+         the precision of clamping aggregation and tracking at run-time.
+
+         For example, with the minimum configuration value we will have 5
+         clamp buckets tracking 20% utilization each. A 25% boosted tasks will
+         be refcounted in the [20..39]% bucket and will set the bucket clamp
+         effective value to 25%.
+         If a second 30% boosted task should be co-scheduled on the same CPU,
+         that task will be refcounted in the same bucket of the first task and
+         it will boost the bucket clamp effective value to 30%.
+         The clamp effective value of a bucket is reset to its nominal value
+         (20% in the example above) when there are no more tasks refcounted in
+         that bucket.
+
+         An additional boost/capping margin can be added to some tasks. In the
+         example above the 25% task will be boosted to 30% until it exits the
+         CPU. If that should be considered not acceptable on certain systems,
+         it's always possible to reduce the margin by increasing the number of
+         clamp buckets to trade off used memory for run-time tracking
+         precision.
+
+         If in doubt, use the default value.
+
+endmenu
+
 #
 # For architectures that want to enable the support for NUMA-affine scheduler
 # balancing logic:
@@ -797,7 +850,7 @@ config BLK_CGROUP
        CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
        CONFIG_BLK_DEV_THROTTLING=y.
 
-       See Documentation/cgroup-v1/blkio-controller.txt for more information.
+       See Documentation/cgroup-v1/blkio-controller.rst for more information.
 
 config CGROUP_WRITEBACK
        bool