1.\" Copyright (c) 2008 Yahoo!, Inc. 2.\" All rights reserved. 3.\" Written by: John Baldwin <jhb@FreeBSD.org> 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. Neither the name of the author nor the names of any co-contributors 14.\" may be used to endorse or promote products derived from this software 15.\" without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd August 19, 2008 32.Dt KVM_GETPCPU 3 33.Os 34.Sh NAME 35.Nm kvm_getmaxcpu , 36.Nm kvm_getpcpu 37.Nd access per-CPU data 38.Sh LIBRARY 39.Lb libkvm 40.Sh SYNOPSIS 41.In sys/param.h 42.In sys/pcpu.h 43.In sys/sysctl.h 44.In kvm.h 45.Ft int 46.Fn kvm_getmaxcpu "kvm_t *kd" 47.Ft void * 48.Fn kvm_getpcpu "kvm_t *kd" "int cpu" 49.Sh DESCRIPTION 50The 51.Fn kvm_getmaxcpu 52and 53.Fn kvm_getpcpu 54functions are used to access the per-CPU data of active processors in the 55kernel indicated by 56.Fa kd . 57The 58.Fn kvm_getmaxcpu 59function returns the maximum number of CPUs supported by the kernel. 60The 61.Fn kvm_getpcpu 62function returns a buffer holding the per-CPU data for a single CPU. 63This buffer is described by the 64.Vt "struct pcpu" 65type. 66The caller is responsible for releasing the buffer via a call to 67.Xr free 3 68when it is no longer needed. 69If 70.Fa cpu 71is not active, then 72.Dv NULL 73is returned instead. 74.Sh CACHING 75These functions cache the nlist values for various kernel variables which are 76reused in successive calls. 77You may call either function with 78.Fa kd 79set to 80.Dv NULL 81to clear this cache. 82.Sh RETURN VALUES 83On success, the 84.Fn kvm_getmaxcpu 85function returns the maximum number of CPUs supported by the kernel. 86If an error occurs, 87it returns -1 instead. 88.Pp 89On success, the 90.Fn kvm_getpcpu 91function returns a pointer to an allocated buffer or 92.Dv NULL. 93If an error occurs, 94it returns -1 instead. 95.Pp 96If either function encounters an error, 97then an error message may be retrieved via 98.Xr kvm_geterr 3. 99.Sh SEE ALSO 100.Xr free 3 , 101.Xr kvm 3 102