108 lines
3.6 KiB
Groff
108 lines
3.6 KiB
Groff
.\" $NetBSD: proc_compare.3,v 1.2 2011/10/21 12:58:53 wiz Exp $
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.\"
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.\" Copyright (c) 2011 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Christos Zoulas.
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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 NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\"
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.Dd October 20, 2011
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.Dt PROC_COMPARE 3
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.Os
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.Sh NAME
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.Nm proc_compare
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.Nd compare two processes' interactivity
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.Sh LIBRARY
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.Lb libutil
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.Sh SYNOPSIS
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.In sys/sysctl.h
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.Ft int
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.Fn "proc_compare" "const struct kinfo_proc2 *p1" "const struct kinfo_lwp *l1" \
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"const struct kinfo_proc2 *p2" "const struct kinfo_lwp *l2"
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.Sh DESCRIPTION
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The
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.Fn proc_compare
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function compares two processes that are on the same terminal for their
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interactivity.
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This means that the process returned is the one that has a better chance
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being the active foreground process on that tty.
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This algorithm is used in the kernel for
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.Dv SIGINFO
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reporting and in userland by
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.Xr w 1 .
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.Pp
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The algorithm used is as follows:
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.Bl -bullet -compact -offset indent
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.It
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If one of them is runnable, it is preferred.
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.It
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If both are runnable, the one with the largest CPU percent is preferred.
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.It
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In a CPU percent tie, the one started more recently wins.
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.It
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If none are runnable, and one of them is a zombie, the non-zombie is preferred
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.It
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If both are zombies, the one started more recently wins.
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.It
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If neither is a zombie, the one with the smaller sleep time wins.
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.It
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In a tie, and one is sleeping in non-interruptible sleep, prefer that one.
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.It
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If both are in the same state, the one started more recently is preferred.
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.El
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In all cases where the most recently started wins, if there was no winner,
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the one with the largest PID wins.
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.Sh RETURN VALUES
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The
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.Fn proc_compare
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function returns
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.Dv 0
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if
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.Fa p1
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is to be preferred
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and
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.Dv 1
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if
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.Fa p2
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is to be preferred.
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.Sh SEE ALSO
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.Xr w 1
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.Sh HISTORY
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The
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.Fn proc_compare
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was extracted from
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.Pa src/sys/kern/tty.c
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and
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.Pa src/usr.bin/w/proc_compare.c
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and merged in
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.Nx 6.0 .
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