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authorZhou Chengming <zhouchengming1@huawei.com>2017-01-22 15:22:35 +0800
committerIngo Molnar <mingo@kernel.org>2017-01-22 10:34:17 +0100
commit3a09b8d45b3c05d49e581831de626927c37599f8 (patch)
tree3b4141675b75814f9f27e28bf0c192ca3d86a0e6 /Documentation/scheduler/sched-rt-group.txt
parentacb04058de49458010c44bb35b849d45113fd668 (diff)
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 <zhouchengming1@huawei.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: corbet@lwn.net Cc: iamyooon@gmail.com Cc: linux-doc@vger.kernel.org Cc: lizefan@huawei.com Link: http://lkml.kernel.org/r/1485069755-44287-1-git-send-email-zhouchengming1@huawei.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/scheduler/sched-rt-group.txt')
-rw-r--r--Documentation/scheduler/sched-rt-group.txt8
1 files changed, 4 insertions, 4 deletions
diff --git a/Documentation/scheduler/sched-rt-group.txt b/Documentation/scheduler/sched-rt-group.txt
index a03f0d944fe6..d8fce3e78457 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