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freebsd/lib/libkvm/kvm_getcptime.3
John Baldwin f110b23b7d Add a new routine kvm_getcptime(3) for fetching the equivalent of
'kern.cp_time'.  For a live kernel it uses the sysctl.  For a crashdump,
it first checks to see if the kernel has a 'cp_time' global symbol.  If
it does, it uses that.  If that doesn't work, when it uses the recently
added kvm_getmaxcpu(3) and kvm_getpcpu(3) routines to walk all the CPUs
and sum up their counters.

MFC after:	1 week
2008-08-19 21:30:36 +00:00

78 lines
2.6 KiB
Groff

.\" Copyright (c) 2008 Yahoo!, Inc.
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.\" Written by: John Baldwin <jhb@FreeBSD.org>
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.\" $FreeBSD$
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.Dd August 19, 2008
.Dt KVM_GETCPTIME 3
.Os
.Sh NAME
.Nm kvm_getcptime
.Nd fetch global CPU time statistics
.Sh LIBRARY
.Lb libkvm
.Sh SYNOPSIS
.In sys/param.h
.In sys/resource.h
.In sys/sysctl.h
.In kvm.h
.Ft int
.Fn kvm_getcptime "kvm_t *kd" "long *cp_time"
.Sh DESCRIPTION
The
.Fn kvm_getcptime
function stores the global CPU time statistics from the kernel
.Fa kd
in the array of counters pointed to by
.Fa cp_time .
Note that
.Fa cp_time
should point to an array of
.Dv CPUSTATES
long integers.
The format of the counters is identical to that output by the
.Va kern.cp_time
sysctl.
.Sh CACHING
This function caches the nlist values for various kernel variables which it
reuses in successive calls.
You may call the function with
.Fa kd
set to
.Dv NULL
to clear this cache.
.Sh RETURN VALUES
The
.Nm kvm_getcptime
function returns 0 on success and -1 on failure.
If an error occurs,
then an error message may be retrieved via
.Xr kvm_geterr 3 .
.Sh SEE ALSO
.Xr kvm 3