19b99e9b9SRobert Watson.\" Copyright (c) 2005 Robert N. M. Watson 29b99e9b9SRobert Watson.\" All rights reserved. 39b99e9b9SRobert Watson.\" 49b99e9b9SRobert Watson.\" Redistribution and use in source and binary forms, with or without 59b99e9b9SRobert Watson.\" modification, are permitted provided that the following conditions 69b99e9b9SRobert Watson.\" are met: 79b99e9b9SRobert Watson.\" 1. Redistributions of source code must retain the above copyright 89b99e9b9SRobert Watson.\" notice, this list of conditions and the following disclaimer. 99b99e9b9SRobert Watson.\" 2. Redistributions in binary form must reproduce the above copyright 109b99e9b9SRobert Watson.\" notice, this list of conditions and the following disclaimer in the 119b99e9b9SRobert Watson.\" documentation and/or other materials provided with the distribution. 129b99e9b9SRobert Watson.\" 139b99e9b9SRobert Watson.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 149b99e9b9SRobert Watson.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 159b99e9b9SRobert Watson.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 169b99e9b9SRobert Watson.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 179b99e9b9SRobert Watson.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 189b99e9b9SRobert Watson.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 199b99e9b9SRobert Watson.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 209b99e9b9SRobert Watson.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 219b99e9b9SRobert Watson.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 229b99e9b9SRobert Watson.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 239b99e9b9SRobert Watson.\" SUCH DAMAGE. 249b99e9b9SRobert Watson.\" 259b99e9b9SRobert Watson.\" $FreeBSD$ 269b99e9b9SRobert Watson.\" 279b99e9b9SRobert Watson.Dd April 7, 2005 289b99e9b9SRobert Watson.Os 299b99e9b9SRobert Watson.Dt SCHED_4BSD 4 309b99e9b9SRobert Watson.Sh NAME 319b99e9b9SRobert Watson.Nm sched_4bsd 32a4be0b3cSRuslan Ermilov.Nd "4.4BSD scheduler" 339b99e9b9SRobert Watson.Sh SYNOPSIS 349b99e9b9SRobert Watson.Cd "options SCHED_4BSD" 359b99e9b9SRobert Watson.Sh DESCRIPTION 36a4be0b3cSRuslan ErmilovThe 379b99e9b9SRobert Watson.Nm 38a4be0b3cSRuslan Ermilovscheduler 399b99e9b9SRobert Watsonis the default system scheduler, providing both high throughput and solid 409b99e9b9SRobert Watsoninteractive response in the presence of load. 419b99e9b9SRobert Watson.Pp 429b99e9b9SRobert WatsonThe following sysctls are relevant to the operation of 439b99e9b9SRobert Watson.Nm : 449b99e9b9SRobert Watson.Bl -tag -width indent 45a4be0b3cSRuslan Ermilov.It Va kern.sched.name 469b99e9b9SRobert WatsonThis read-only sysctl reports the name of the active scheduler. 47a4be0b3cSRuslan Ermilov.It Va kern.sched.quantum 489b99e9b9SRobert WatsonThis read-write sysctl reports or sets the length of the quantum (in 499b99e9b9SRobert Watsonmicro-seconds) granted to a thread. 50a4be0b3cSRuslan Ermilov.It Va kern.sched.ipiwakeup.enabled 519b99e9b9SRobert WatsonThis read-write sysctl sets whether or not the scheduler will generate an 529b99e9b9SRobert Watsoninter-processor interrupt (IPI) to an idle CPU when a thread is woken up. 539b99e9b9SRobert WatsonOtherwise, idle CPUs will wait until the next clock tick before looking for 549b99e9b9SRobert Watsonnew work. 55a4be0b3cSRuslan Ermilov.It Va kern.sched.preemption 569b99e9b9SRobert WatsonThis read-only sysctl reports whether or not the kernel is configured to 579b99e9b9SRobert Watsonsupport preemption, which reduces the latency to run lower priority threads 589b99e9b9SRobert Watsonon wakeup. 599b99e9b9SRobert Watson.El 609b99e9b9SRobert Watson.Pp 619b99e9b9SRobert WatsonSome sysctls will be available only on systems supporting SMP. 629b99e9b9SRobert Watson.Sh SEE ALSO 639b99e9b9SRobert Watson.Xr sched_ule 4 , 649b99e9b9SRobert Watson.Xr sysctl 8 659b99e9b9SRobert Watson.Sh HISTORY 669b99e9b9SRobert WatsonThe 679b99e9b9SRobert Watson.Nm 689b99e9b9SRobert Watsonscheduler has been present, in various forms, since the inception of 699b99e9b9SRobert Watson.Bx . 709b99e9b9SRobert Watson.Sh BUGS 719b99e9b9SRobert WatsonWhile a highly robust and time-tested scheduler, 729b99e9b9SRobert Watson.Nm 734953b2fbSJoel Dahllacks specific knowledge of how to schedule advantageously in non-symmetric 749b99e9b9SRobert Watsonprocessor configurations, such as hyper-threading. 75