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136 lines
5.1 KiB
Perl
136 lines
5.1 KiB
Perl
.\" Copyright (c) 1983, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)1.6.t 8.1 (Berkeley) 6/8/93
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.\"
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.sh "Resource controls
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.NH 3
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Process priorities
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.PP
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The system gives CPU scheduling priority to processes that have not used
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CPU time recently. This tends to favor interactive processes and
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processes that execute only for short periods.
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It is possible to determine the priority currently
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assigned to a process, process group, or the processes of a specified user,
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or to alter this priority using the calls:
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.DS
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._d
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#define PRIO_PROCESS 0 /* process */
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#define PRIO_PGRP 1 /* process group */
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#define PRIO_USER 2 /* user id */
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prio = getpriority(which, who);
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result int prio; int which, who;
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setpriority(which, who, prio);
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int which, who, prio;
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.DE
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The value \fIprio\fP is in the range \-20 to 20.
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The default priority is 0; lower priorities cause more
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favorable execution.
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The \fIgetpriority\fP call returns the highest priority (lowest numerical value)
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enjoyed by any of the specified processes.
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The \fIsetpriority\fP call sets the priorities of all of the
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specified processes to the specified value.
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Only the super-user may lower priorities.
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.NH 3
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Resource utilization
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.PP
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The resources used by a process are returned by a \fIgetrusage\fP call,
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returning information in a structure defined in \fI<sys/resource.h>\fP:
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.DS
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._d
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#define RUSAGE_SELF 0 /* usage by this process */
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#define RUSAGE_CHILDREN -1 /* usage by all children */
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getrusage(who, rusage)
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int who; result struct rusage *rusage;
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._f
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struct rusage {
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struct timeval ru_utime; /* user time used */
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struct timeval ru_stime; /* system time used */
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int ru_maxrss; /* maximum core resident set size: kbytes */
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int ru_ixrss; /* integral shared memory size (kbytes*sec) */
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int ru_idrss; /* unshared data memory size */
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int ru_isrss; /* unshared stack memory size */
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int ru_minflt; /* page-reclaims */
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int ru_majflt; /* page faults */
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int ru_nswap; /* swaps */
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int ru_inblock; /* block input operations */
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int ru_oublock; /* block output operations */
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int ru_msgsnd; /* messages sent */
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int ru_msgrcv; /* messages received */
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int ru_nsignals; /* signals received */
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int ru_nvcsw; /* voluntary context switches */
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int ru_nivcsw; /* involuntary context switches */
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};
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.DE
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The \fIwho\fP parameter specifies whose resource usage is to be returned.
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The resources used by the current process, or by all
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the terminated children of the current process may be requested.
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.NH 3
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Resource limits
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.PP
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The resources of a process for which limits are controlled by the
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kernel are defined in \fI<sys/resource.h>\fP, and controlled by the
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\fIgetrlimit\fP and \fIsetrlimit\fP calls:
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.DS
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._d
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#define RLIMIT_CPU 0 /* cpu time in milliseconds */
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#define RLIMIT_FSIZE 1 /* maximum file size */
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#define RLIMIT_DATA 2 /* maximum data segment size */
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#define RLIMIT_STACK 3 /* maximum stack segment size */
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#define RLIMIT_CORE 4 /* maximum core file size */
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#define RLIMIT_RSS 5 /* maximum resident set size */
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#define RLIM_NLIMITS 6
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#define RLIM_INFINITY 0x7f\&f\&f\&f\&f\&f\&f
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._f
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struct rlimit {
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int rlim_cur; /* current (soft) limit */
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int rlim_max; /* hard limit */
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};
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getrlimit(resource, rlp)
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int resource; result struct rlimit *rlp;
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setrlimit(resource, rlp)
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int resource; struct rlimit *rlp;
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.DE
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.PP
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Only the super-user can raise the maximum limits.
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Other users may only
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alter \fIrlim_cur\fP within the range from 0 to \fIrlim_max\fP
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or (irreversibly) lower \fIrlim_max\fP.
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