Commit-ID: 3a09b8d45b3c05d49e581831de626927c37599f8 Gitweb: http://git.kernel.org/tip/3a09b8d45b3c05d49e581831de626927c37599f8 Author: Zhou Chengming <[email protected]> AuthorDate: Sun, 22 Jan 2017 15:22:35 +0800 Committer: Ingo Molnar <[email protected]> CommitDate: Sun, 22 Jan 2017 10:34:17 +0100
sched/Documentation/sched-rt-group: Fix incorrect example I feel that the example given in the document to show the possibility of task starvation of configurable period is wrong. The example says group A and B both have 50% bandwidth, and a while (1) loop in A will run for the full period of B and can starve B's tasks. So I think the runtime of group A should be 50000us, then the period and runtime of group B should be 50000us and 25000us. Signed-off-by: Zhou Chengming <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- Documentation/scheduler/sched-rt-group.txt | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/Documentation/scheduler/sched-rt-group.txt b/Documentation/scheduler/sched-rt-group.txt index a03f0d9..d8fce3e 100644 --- a/Documentation/scheduler/sched-rt-group.txt +++ b/Documentation/scheduler/sched-rt-group.txt @@ -158,11 +158,11 @@ as its prone to starvation without deadline scheduling. Consider two sibling groups A and B; both have 50% bandwidth, but A's period is twice the length of B's. -* group A: period=100000us, runtime=10000us - - this runs for 0.01s once every 0.1s +* group A: period=100000us, runtime=50000us + - this runs for 0.05s once every 0.1s -* group B: period= 50000us, runtime=10000us - - this runs for 0.01s twice every 0.1s (or once every 0.05 sec). +* group B: period= 50000us, runtime=25000us + - this runs for 0.025s twice every 0.1s (or once every 0.05 sec). This means that currently a while (1) loop in A will run for the full period of B and can starve B's tasks (assuming they are of lower priority) for a whole
