Documentation/scheduler/sched-bwc.rst

11 The bandwidth allowed for a group is specified using a quota and period. Within
12 each given "period" (microseconds), a task group is allocated up to "quota"
13 microseconds of CPU time. That quota is assigned to per-cpu run queues in
14 slices as threads in the cgroup become runnable. Once all quota has been
15 assigned any additional requests for quota will result in those threads being
17 period when the quota is replenished.
19 A group's unassigned quota is globally tracked, being refreshed back to
43 The minimum quota allowed for the quota or period is 1ms. There is also an
95 	a. it fully consumes its own quota within a period
96 	b. a parent's quota is fully consumed within its period
114 quota as well as the entirety of each cpu-local slice in each period. As a
119 allows applications to briefly burst past their quota limits by the amount of
122 applies if quota had been assigned to a cpu and then not fully used or returned
124 As a result, this mechanism still strictly limits the task group to quota
128 small quota limits on high core count machines. It also eliminates the
130 quota amounts of cpu. Another way to say this, is that by allowing the unused
132 possibility of wastefully expiring quota on cpu-local silos that don't need a
139 will use up to 1ms additional quota in some periods, thereby preventing the
140 cpu-bound application from fully using its quota by that same amount. In these
143 have remaining quota. This runtime discrepancy will be made up in the following
150 	If period is 250ms and quota is also 250ms, the group will get
153 	# echo 250000 > cpu.cfs_quota_us /* quota = 250ms */
158    With 500ms period and 1000ms quota, the group can get 2 CPUs worth of
161 	# echo 1000000 > cpu.cfs_quota_us /* quota = 1000ms */
168    With 50ms period, 10ms quota will be equivalent to 20% of 1 CPU::
170 	# echo 10000 > cpu.cfs_quota_us /* quota = 10ms */