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authorLinus Torvalds <torvalds@linux-foundation.org>2017-02-20 12:52:55 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-20 12:52:55 -0800
commit828cad8ea05d194d8a9452e0793261c2024c23a2 (patch)
tree0ad7c7e044cdcfe75d78da0b52eb2358d4686e02 /Documentation
parent60c906bab124a0627fba04c9ca5e61bba4747c0c (diff)
parentbb3bac2ca9a3a5b7fa601781adf70167a0449d75 (diff)
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar: "The main changes in this (fairly busy) cycle were: - There was a class of scheduler bugs related to forgetting to update the rq-clock timestamp which can cause weird and hard to debug problems, so there's a new debug facility for this: which uncovered a whole lot of bugs which convinced us that we want to keep the debug facility. (Peter Zijlstra, Matt Fleming) - Various cputime related updates: eliminate cputime and use u64 nanoseconds directly, simplify and improve the arch interfaces, implement delayed accounting more widely, etc. - (Frederic Weisbecker) - Move code around for better structure plus cleanups (Ingo Molnar) - Move IO schedule accounting deeper into the scheduler plus related changes to improve the situation (Tejun Heo) - ... plus a round of sched/rt and sched/deadline fixes, plus other fixes, updats and cleanups" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (85 commits) sched/core: Remove unlikely() annotation from sched_move_task() sched/autogroup: Rename auto_group.[ch] to autogroup.[ch] sched/topology: Split out scheduler topology code from core.c into topology.c sched/core: Remove unnecessary #include headers sched/rq_clock: Consolidate the ordering of the rq_clock methods delayacct: Include <uapi/linux/taskstats.h> sched/core: Clean up comments sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds sched/clock: Add dummy clear_sched_clock_stable() stub function sched/cputime: Remove generic asm headers sched/cputime: Remove unused nsec_to_cputime() s390, sched/cputime: Remove unused cputime definitions powerpc, sched/cputime: Remove unused cputime definitions s390, sched/cputime: Make arch_cpu_idle_time() to return nsecs ia64, sched/cputime: Remove unused cputime definitions ia64: Convert vtime to use nsec units directly ia64, sched/cputime: Move the nsecs based cputime headers to the last arch using it sched/cputime: Remove jiffies based cputime sched/cputime, vtime: Return nsecs instead of cputime_t to account sched/cputime: Complete nsec conversion of tick based accounting ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/scheduler/sched-deadline.txt6
-rw-r--r--Documentation/scheduler/sched-rt-group.txt8
2 files changed, 10 insertions, 4 deletions
diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt
index 8e37b0ba2c9d..cbc1b46cbf70 100644
--- a/Documentation/scheduler/sched-deadline.txt
+++ b/Documentation/scheduler/sched-deadline.txt
@@ -408,6 +408,11 @@ CONTENTS
* the new scheduling related syscalls that manipulate it, i.e.,
sched_setattr() and sched_getattr() are implemented.
+ For debugging purposes, the leftover runtime and absolute deadline of a
+ SCHED_DEADLINE task can be retrieved through /proc/<pid>/sched (entries
+ dl.runtime and dl.deadline, both values in ns). A programmatic way to
+ retrieve these values from production code is under discussion.
+
4.3 Default behavior
---------------------
@@ -476,6 +481,7 @@ CONTENTS
Still missing:
+ - programmatic way to retrieve current runtime and absolute deadline
- refinements to deadline inheritance, especially regarding the possibility
of retaining bandwidth isolation among non-interacting tasks. This is
being studied from both theoretical and practical points of view, and
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