diff options
Diffstat (limited to 'Documentation/scheduler')
| -rw-r--r-- | Documentation/scheduler/sched-nice-design.txt | 2 | ||||
| -rw-r--r-- | Documentation/scheduler/sched-rt-group.txt | 20 |
2 files changed, 20 insertions, 2 deletions
diff --git a/Documentation/scheduler/sched-nice-design.txt b/Documentation/scheduler/sched-nice-design.txt index e2bae5a577e..3ac1e46d536 100644 --- a/Documentation/scheduler/sched-nice-design.txt +++ b/Documentation/scheduler/sched-nice-design.txt @@ -55,7 +55,7 @@ To sum it up: we always wanted to make nice levels more consistent, but within the constraints of HZ and jiffies and their nasty design level coupling to timeslices and granularity it was not really viable. -The second (less frequent but still periodically occuring) complaint +The second (less frequent but still periodically occurring) complaint about Linux's nice level support was its assymetry around the origo (which you can see demonstrated in the picture above), or more accurately: the fact that nice level behavior depended on the _absolute_ diff --git a/Documentation/scheduler/sched-rt-group.txt b/Documentation/scheduler/sched-rt-group.txt index 5ba4d3fc625..1df7f9cdab0 100644 --- a/Documentation/scheduler/sched-rt-group.txt +++ b/Documentation/scheduler/sched-rt-group.txt @@ -4,6 +4,7 @@ CONTENTS ======== +0. WARNING 1. Overview 1.1 The problem 1.2 The solution @@ -14,6 +15,23 @@ CONTENTS 3. Future plans +0. WARNING +========== + + Fiddling with these settings can result in an unstable system, the knobs are + root only and assumes root knows what he is doing. + +Most notable: + + * very small values in sched_rt_period_us can result in an unstable + system when the period is smaller than either the available hrtimer + resolution, or the time it takes to handle the budget refresh itself. + + * very small values in sched_rt_runtime_us can result in an unstable + system when the runtime is so small the system has difficulty making + forward progress (NOTE: the migration thread and kstopmachine both + are real-time processes). + 1. Overview =========== @@ -169,7 +187,7 @@ get their allocated time. Implementing SCHED_EDF might take a while to complete. Priority Inheritance is the biggest challenge as the current linux PI infrastructure is geared towards -the limited static priority levels 0-139. With deadline scheduling you need to +the limited static priority levels 0-99. With deadline scheduling you need to do deadline inheritance (since priority is inversely proportional to the deadline delta (deadline - now). |