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Subject[tip:sched/urgent] sched/deadline: Fix the description of runtime accounting in the documentation
Commit-ID:  5c0342ca7ef17220d8dd2da68d0d349c26ab19df
Gitweb: https://git.kernel.org/tip/5c0342ca7ef17220d8dd2da68d0d349c26ab19df
Author: Claudio Scordino <claudio@evidence.eu.com>
AuthorDate: Tue, 14 Nov 2017 12:19:26 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 16 Nov 2017 09:00:35 +0100

sched/deadline: Fix the description of runtime accounting in the documentation

Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Acked-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1510658366-28995-1-git-send-email-claudio@evidence.eu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
Documentation/scheduler/sched-deadline.txt | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt
index e89e36e..8ce78f8 100644
--- a/Documentation/scheduler/sched-deadline.txt
+++ b/Documentation/scheduler/sched-deadline.txt
@@ -204,10 +204,17 @@ CONTENTS
It does so by decrementing the runtime of the executing task Ti at a pace equal
to

- dq = -max{ Ui, (1 - Uinact) } dt
+ dq = -max{ Ui / Umax, (1 - Uinact - Uextra) } dt

- where Uinact is the inactive utilization, computed as (this_bq - running_bw),
- and Ui is the bandwidth of task Ti.
+ where:
+
+ - Ui is the bandwidth of task Ti;
+ - Umax is the maximum reclaimable utilization (subjected to RT throttling
+ limits);
+ - Uinact is the (per runqueue) inactive utilization, computed as
+ (this_bq - running_bw);
+ - Uextra is the (per runqueue) extra reclaimable utilization
+ (subjected to RT throttling limits).


Let's now see a trivial example of two deadline tasks with runtime equal
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