1 .\" Copyright (c) 2008 Yahoo!, Inc.
2 .\" All rights reserved.
3 .\" Written by: John Baldwin <jhb@FreeBSD.org>
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
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.
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
38 .Nd access per-CPU data
47 .Fn kvm_dpcpu_setcpu "kvm_t *kd" "u_int cpu"
49 .Fn kvm_getmaxcpu "kvm_t *kd"
51 .Fn kvm_getpcpu "kvm_t *kd" "int cpu"
53 .Fn kvm_read_zpcpu "kvm_t *kd" "void *buf" "u_long base" "size_t size" "int cpu"
55 .Fn kvm_counter_u64_fetch "kvm_t *kd" "u_long base"
58 .Fn kvm_dpcpu_setcpu ,
62 functions are used to access the per-CPU data of active processors in the
65 Per-CPU storage comes in two flavours: data stored directly in a
67 associated with each CPU, and dynamic per-CPU storage (DPCPU), in which a
68 single kernel symbol refers to different data depending on what CPU it is
73 function returns the maximum number of CPUs supported by the kernel.
77 function returns a buffer holding the per-CPU data for a single CPU.
78 This buffer is described by the
81 The caller is responsible for releasing the buffer via a call to
83 when it is no longer needed.
92 function is used to obtain private per-CPU copy from a
97 argument as base address of an allocation and copyies
101 from the part of allocation that is private to
105 .Fn kvm_counter_u64_fetch
106 function fetches value of a
112 Symbols for dynamic per-CPU data are accessed via
114 as with other symbols.
116 maintains a notion of the "current CPU", set by
117 .Xr kvm_dpcpu_setcpu ,
119 Once another CPU is selected,
121 will return pointers to that data on the appropriate CPU.
126 cache the nlist values for various kernel variables which are
127 reused in successive calls.
128 You may call either function with
136 function returns the maximum number of CPUs supported by the kernel.
138 it returns -1 instead.
142 function returns a pointer to an allocated buffer or
145 it returns -1 instead.
149 call returns 0; if an error occurs, it returns -1 instead.
153 function returns number of bytes copied.
154 If an error occurs, it returns -1 instead.
156 If any function encounters an error,
157 then an error message may be retrieved via