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| author | Zhou Chengming <zhouchengming1@huawei.com> | 2017-01-22 10:22:35 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-01-22 12:34:17 +0300 |
| commit | 3a09b8d45b3c05d49e581831de626927c37599f8 (patch) | |
| tree | 3b4141675b75814f9f27e28bf0c192ca3d86a0e6 /Documentation/scheduler | |
| parent | acb04058de49458010c44bb35b849d45113fd668 (diff) | |
| download | linux-3a09b8d45b3c05d49e581831de626927c37599f8.tar.xz | |
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')
| -rw-r--r-- | Documentation/scheduler/sched-rt-group.txt | 8 |
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 |