2004-11-03 13:51:07 +00:00
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.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, write to the Free
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.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
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.\" USA.
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.\"
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.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
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.\" First version written
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.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
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.\" revision
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.\"
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2011-10-16 04:45:57 +00:00
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.TH SCHED_RR_GET_INTERVAL 2 2011-10-16 "Linux" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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sched_rr_get_interval \- get the SCHED_RR interval for the named process
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2004-11-03 13:51:07 +00:00
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.SH SYNOPSIS
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.B #include <sched.h>
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.sp
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2007-07-16 18:57:34 +00:00
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.BI "int sched_rr_get_interval(pid_t " pid ", struct timespec * " tp );
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.SH DESCRIPTION
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2005-10-19 06:54:38 +00:00
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.BR sched_rr_get_interval ()
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2011-10-16 04:50:04 +00:00
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writes into the
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.I timespec
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structure pointed to by
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.I tp
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the round-robin time quantum for the process identified by
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.IR pid .
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The specified process should be running under the
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.B SCHED_RR
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scheduling policy.
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2007-04-05 12:50:59 +00:00
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2011-10-16 04:50:04 +00:00
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The
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.I timespec
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structure has the following form:
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2007-12-19 06:57:44 +00:00
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.in +4n
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.nf
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struct timespec {
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time_t tv_sec; /* seconds */
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long tv_nsec; /* nanoseconds */
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};
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.fi
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.in
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If
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.I pid
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is zero, the time quantum for the calling process is written into
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.IR *tp .
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2008-04-23 09:10:40 +00:00
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.\" FIXME . On Linux, sched_rr_get_interval()
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.\" returns the timeslice for SCHED_OTHER processes -- this timeslice
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.\" is influenced by the nice value.
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.\" For SCHED_FIFO processes, this always returns 0.
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.\"
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2007-04-05 14:37:59 +00:00
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.\" The round-robin time quantum value is not alterable under Linux
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.\" 1.3.81.
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2007-04-12 22:42:49 +00:00
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.\"
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.SH "RETURN VALUE"
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On success,
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.BR sched_rr_get_interval ()
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returns 0.
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On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EFAULT
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eventfd.2, futex.2, mmap2.2, open.2, pciconfig_read.2, ptrace.2, reboot.2, request_key.2, sched_rr_get_interval.2, splice.2, stat.2, sync_file_range.2, syscalls.2, timer_create.2, vm86.2, pthread_attr_setscope.3, core.5, proc.5, aio.7, futex.7, netlink.7, time.7: Global fix: "userspace" ==> "user space" or "user-space"
Existing pages variously use "userspace or "user space".
But, "userspace" is not quite an English word.
So change "userspace" to "user space" or, when used
attributively, "user-space".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-10-21 06:04:42 +00:00
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Problem with copying information to user space.
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.TP
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.B EINVAL
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Invalid pid.
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.TP
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.B ENOSYS
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The system call is not yet implemented (only on rather old kernels).
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.TP
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.B ESRCH
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2011-10-16 04:54:16 +00:00
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Could not find a process with the ID
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.IR pid .
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.SH "CONFORMING TO"
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2006-08-03 13:57:17 +00:00
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POSIX.1-2001.
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2007-05-18 10:39:45 +00:00
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.SH NOTES
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2011-10-16 04:45:57 +00:00
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POSIX systems on which
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.BR sched_rr_get_interval ()
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is available define
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.B _POSIX_PRIORITY_SCHEDULING
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2011-10-16 04:50:04 +00:00
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in
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.IR <unistd.h> .
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.SS Linux Notes
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POSIX does not specify any mechanism for controlling the size of the
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round-robin time quantum.
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2011-10-16 05:01:47 +00:00
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Older Linux kernels provide a (nonportable) method of doing this.
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2007-04-05 14:37:59 +00:00
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The quantum can be controlled by adjusting the process's nice value (see
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.BR setpriority (2)).
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Assigning a negative (i.e., high) nice value results in a longer quantum;
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assigning a positive (i.e., low) nice value results in a shorter quantum.
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The default quantum is 0.1 seconds;
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the degree to which changing the nice value affects the
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quantum has varied somewhat across kernel versions.
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2011-10-16 05:01:47 +00:00
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Since Linux 2.6.24,
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.\" commit a4ec24b48ddef1e93f7578be53270f0b95ad666c
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the
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.BR SCHED_RR
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quantum cannot be modified.
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2007-04-05 14:37:59 +00:00
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.\" .SH BUGS
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2007-06-21 22:55:04 +00:00
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.\" As of Linux 1.3.81
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.\" .BR sched_rr_get_interval ()
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.\" returns with error
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.\" ENOSYS, because SCHED_RR has not yet been fully implemented and tested
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.\" properly.
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2004-11-03 13:51:07 +00:00
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.SH "SEE ALSO"
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.BR sched_setscheduler (2)
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has a description of the Linux scheduling scheme.
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.PP
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.I Programming for the real world \- POSIX.4
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arch_prctl.2, fcntl.2, flock.2, get_robust_list.2, getpriority.2, ioprio_set.2, migrate_pages.2, mmap.2, mremap.2, msync.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, select.2, socket.2, subpage_prot.2, unshare.2, btree.3, dbopen.3, dl_iterate_phdr.3, dlopen.3, getnameinfo.3, hash.3, lockf.3, netlink.3, recno.3, rpc.3, xdr.3, cciss.4, console_ioctl.4, hpsa.4, initrd.4, msr.4, rtc.4, st.4, hosts.5, services.5, tzfile.5, aio.7, arp.7, capabilities.7, cpuset.7, feature_test_macros.7, futex.7, inotify.7, ip.7, ipv6.7, iso_8859-16.7, iso_8859-2.7, koi8-r.7, math_error.7, netlink.7, packet.7, pthreads.7, raw.7, spufs.7, udplite.7, uri.7, x25.7: Global fix: Various consistency fixes for SEE ALSO
Coauthored-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-09-24 07:53:22 +00:00
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by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0.
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