[src/trunk]: src/share/man/man7 Document kern.sched sysctl variables.

[hubertf <hubertf%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/7d110e3164a4
branches:  trunk
changeset: 820428:7d110e3164a4
user:      hubertf <hubertf%NetBSD.org@localhost>
date:      Mon Jan 09 20:08:26 2017 +0000

description:
Document kern.sched sysctl variables.

diffstat:

 share/man/man7/sysctl.7 |  104 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 100 insertions(+), 4 deletions(-)

diffs (125 lines):

diff -r 1537e3904151 -r 7d110e3164a4 share/man/man7/sysctl.7
--- a/share/man/man7/sysctl.7   Mon Jan 09 20:05:29 2017 +0000
+++ b/share/man/man7/sysctl.7   Mon Jan 09 20:08:26 2017 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: sysctl.7,v 1.107 2017/01/08 14:28:42 wiz Exp $
+.\"    $NetBSD: sysctl.7,v 1.108 2017/01/09 20:08:26 hubertf Exp $
 .\"
 .\" Copyright (c) 1993
 .\"    The Regents of the University of California.  All rights reserved.
@@ -355,7 +355,7 @@
 .It kern.rtc_offset    integer yes
 .It kern.saved_ids     integer no
 .It kern.sbmax integer yes
-.\".It kern.sched      node    not applicable
+.It kern.sched node    not applicable
 .It kern.securelevel   integer raise only
 .It kern.somaxkva      integer yes
 .It kern.synchronized_io       integer no
@@ -1057,8 +1057,104 @@
 .It Li kern.securelevel ( Dv KERN_SECURELVL )
 See
 .Xr secmodel_securelevel 9 .
-.\" .It Li kern.sched
-.\" XXX: Undocumented.
+.It Li kern.sched ( dynamic )
+Influence the scheduling of LWPs, their priorisation and how they are
+distributed on and moved between CPUs.
+.Bl -column "kern.sched.balance_period" "integer" "Changeable" -offset indent
+.It Sy Third level name           Sy Type       Sy Changeable
+.It kern.sched.cacheht_time       integer       yes
+.It kern.sched.balance_period     integer       yes
+.It kern.sched.average_weight     integer       yes
+.It kern.sched.min_catch          integer       yes
+.It kern.sched.timesoftints       integer       yes
+.It kern.sched.kpreempt_pri       integer       yes
+.It kern.sched.upreempt_pri       integer       yes
+.It kern.sched.maxts      integer       yes
+.It kern.sched.mints      integer       yes 
+.It kern.sched.name       string        no 
+.It kern.sched.rtts       integer       no
+.It kern.sched.pri_min    integer       no
+.It kern.sched.pri_max    integer       no
+.El
+.Pp
+The variables are as follows:
+.Bl -tag -width "123456"
+.It Li kern.sched.cacheht_time ( dynamic )
+Cache hotness time in which a LWP is kept on one particular CPU
+and not moved to another CPU. This reduces the overhead of flushing
+and reloading caches.  
+Defaults to 3ms.
+Needs to be given in 
+.Dq hz
+units, see
+.Xr mstohz 9 .
+.It Li kern.sched.balance_period ( dynamic )
+Interval at which the CPU queues are checked for re-balancing.
+Defaults to 300ms.
+Needs to be given in 
+.Dq hz
+units, see
+.Xr mstohz 9 .
+.It Li kern.sched.average_weight ( dynamic )
+Can be used to influence how likely LWPs are to be migrated from
+one CPU's queue of LWPs that are ready to run to a different, idle CPU. 
+The value gives the percentage for weighting the average count of
+migratable threads from the past against the current number of
+migratable threads. 
+A small value gives more weight to the past, a larger values more weight 
+on the current situation.
+Defaults to 50 and must be between 0 and 100. 
+.It Li kern.sched.min_catch ( dynamic )
+Minimum count of migratable (runable) threads for catching (stealing)
+from another CPU.
+Defaults to 1 but can be increased to decrease chance of thread
+migration between CPUs. 
+.It Li kern.sched.timesoftints ( dynamic )
+Enable tracking of CPU time for soft interrupts
+as part of a LWP's real execution time.
+Set to a non-zero value to enable,
+and see
+.Xr ps 1
+for printing CPU times.
+.It Li kern.sched.kpreempt_pri ( dynamic )
+Minimum priority to trigger kernel preemption.
+.It Li kern.sched.upreempt_pri ( dynamic )
+Minimum priority to trigger user preemption.
+.It Li kern.sched.maxts ( dynamic )
+Scheduler specific maximal time quantum (in milliseconds).
+Must be set to a value larger than
+.Dq mints
+and between 10 and
+.Dq hz 
+as given by the
+.Dv kern.clockrate
+sysctl.
+Provided by the M2 scheduler.
+.It Li kern.sched.mints ( dynamic )
+Scheduler specific minimal time quantum (in milliseconds).
+Must be set to a value smaller than
+.Dq maxts
+and between 1 and
+.Dq hz 
+as given by the
+.Dq kern.clockrate
+sysctl.
+Provided by the M2 scheduler.
+.It Li kern.sched.name ( dynamic )
+Scheduler name. 
+Provided both by the M2 and the 4BSD scheduler.
+.It Li kern.sched.rtts ( dynamic )
+Fixed scheduler specific round-robin time quantum in milliseconds.
+Provided both by the M2 and the 4BSD scheduler.
+.It Li kern.sched.pri_min ( dynamic )
+Minimal POSIX real-time priority.
+See
+.Xr sched 3 .
+.It Li kern.sched.pri_max ( dynamic )
+Maximal POSIX real-time priority.
+See
+.Xr sched 3 .
+.El
 .It Li kern.somaxkva ( Dv KERN_SOMAXKVA )
 Maximum amount of kernel memory to be used for socket buffers.
 .\" XXX units?