cgroups.7: Add details on 'cpu' CFS bandwidth control

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man7/cgroups.7 b/man7/cgroups.7
index 324eba0a94fc456f718f3d5e78a205d17c060b00..225821039f908cf09c2f4d7f4f1a697ad7282d30 100644 (file)
--- a/man7/cgroups.7
+++ b/man7/cgroups.7
@@ -241,7 +241,17 @@ kernel configuration option.
 Cgroups can be guaranteed a minimum number of "CPU shares"
 when a system is busy.
 This does not limit a cgroup's CPU usage if the CPUs are not busy.
-
+For further information, see
+.IR Documentation/scheduler/sched-design-CFS.txt .
+
+In Linux 3.2,
+this controller was extended to provide CPU "bandwidth" control.
+If the kernel is configured with
+.BR COONFIG_CFS_BANDWIDTH ,
+then within each scheduling period
+(defined via a file in the cgroup directory), it is possible to define
+an upper limit on the CPU time allocated to the processes in a cgroup.
+This upper limit applies even if there is no other competition for the CPU.
 Further information can be found in the kernel source file
 .IR Documentation/scheduler/sched\-bwc.txt .
 .TP