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
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| 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: head/lib/libkvm/kvm_getpcpu.3 235286 2012-05-11 20:06:46Z gjb $
| 29.\" $FreeBSD: head/lib/libkvm/kvm_getpcpu.3 249344 2013-04-10 20:26:53Z glebius $
|
30.\"
| 30.\"
|
31.Dd February 28, 2010
| 31.Dd April 11, 2013
|
32.Dt KVM_GETPCPU 3
33.Os
34.Sh NAME
35.Nm kvm_dpcpu_setcpu
36.Nm kvm_getmaxcpu ,
37.Nm kvm_getpcpu
38.Nd access per-CPU data
39.Sh LIBRARY
40.Lb libkvm
41.Sh SYNOPSIS
42.In sys/param.h
43.In sys/pcpu.h
44.In sys/sysctl.h
45.In kvm.h
46.Ft int
47.Fn kvm_dpcpu_setcpu "kvm_t *kd" "u_int cpu"
48.Ft int
49.Fn kvm_getmaxcpu "kvm_t *kd"
50.Ft void *
51.Fn kvm_getpcpu "kvm_t *kd" "int cpu"
| 32.Dt KVM_GETPCPU 3
33.Os
34.Sh NAME
35.Nm kvm_dpcpu_setcpu
36.Nm kvm_getmaxcpu ,
37.Nm kvm_getpcpu
38.Nd access per-CPU data
39.Sh LIBRARY
40.Lb libkvm
41.Sh SYNOPSIS
42.In sys/param.h
43.In sys/pcpu.h
44.In sys/sysctl.h
45.In kvm.h
46.Ft int
47.Fn kvm_dpcpu_setcpu "kvm_t *kd" "u_int cpu"
48.Ft int
49.Fn kvm_getmaxcpu "kvm_t *kd"
50.Ft void *
51.Fn kvm_getpcpu "kvm_t *kd" "int cpu"
|
| 52.Ft ssize_t
53.Fn kvm_read_zpcpu "kvm_t *kd" "void *buf" "u_long base" "size_t size" "int cpu"
54.Ft uint64_t
55.Fn kvm_counter_u64_fetch "kvm_t *kd" "u_long base"
|
52.Sh DESCRIPTION
53The
54.Fn kvm_dpcpu_setcpu ,
55.Fn kvm_getmaxcpu ,
56and
57.Fn kvm_getpcpu
58functions are used to access the per-CPU data of active processors in the
59kernel indicated by
60.Fa kd .
61Per-CPU storage comes in two flavours: data stored directly in a
62.Vt "struct pcpu"
63associated with each CPU, and dynamic per-CPU storage (DPCPU), in which a
64single kernel symbol refers to different data depending on what CPU it is
65accessed from.
66.Pp
67The
68.Fn kvm_getmaxcpu
69function returns the maximum number of CPUs supported by the kernel.
70.Pp
71The
72.Fn kvm_getpcpu
73function returns a buffer holding the per-CPU data for a single CPU.
74This buffer is described by the
75.Vt "struct pcpu"
76type.
77The caller is responsible for releasing the buffer via a call to
78.Xr free 3
79when it is no longer needed.
80If
81.Fa cpu
82is not active, then
83.Dv NULL
84is returned instead.
85.Pp
| 56.Sh DESCRIPTION
57The
58.Fn kvm_dpcpu_setcpu ,
59.Fn kvm_getmaxcpu ,
60and
61.Fn kvm_getpcpu
62functions are used to access the per-CPU data of active processors in the
63kernel indicated by
64.Fa kd .
65Per-CPU storage comes in two flavours: data stored directly in a
66.Vt "struct pcpu"
67associated with each CPU, and dynamic per-CPU storage (DPCPU), in which a
68single kernel symbol refers to different data depending on what CPU it is
69accessed from.
70.Pp
71The
72.Fn kvm_getmaxcpu
73function returns the maximum number of CPUs supported by the kernel.
74.Pp
75The
76.Fn kvm_getpcpu
77function returns a buffer holding the per-CPU data for a single CPU.
78This buffer is described by the
79.Vt "struct pcpu"
80type.
81The caller is responsible for releasing the buffer via a call to
82.Xr free 3
83when it is no longer needed.
84If
85.Fa cpu
86is not active, then
87.Dv NULL
88is returned instead.
89.Pp
|
| 90The
91.Fn kvm_read_zpcpu
92function is used to obtain private per-CPU copy from a
93.Dv UMA_ZONE_PCPU
94.Xr zone 9 .
95It takes
96.Fa base
97argument as base address of an allocation and copyies
98.Fa size
99bytes into
100.Fa buf
101from the part of allocation that is private to
102.Fa cpu .
103.Pp
104The
105.Fn kvm_counter_u64_fetch
106function fetches value of a
107.Xr counter 9
108pointed by
109.Fa base
110address.
111.Pp
|
86Symbols for dynamic per-CPU data are accessed via
87.Xr kvm_nlist 3
88as with other symbols.
89.Nm libkvm
90maintains a notion of the "current CPU", set by
91.Xr kvm_dpcpu_setcpu ,
92which defaults to 0.
93Once another CPU is selected,
94.Xr kvm_nlist 3
95will return pointers to that data on the appropriate CPU.
96.Sh CACHING
97.Fn kvm_getmaxcpu
98and
99.Fn kvm_getpcpu
100cache the nlist values for various kernel variables which are
101reused in successive calls.
102You may call either function with
103.Fa kd
104set to
105.Dv NULL
106to clear this cache.
107.Sh RETURN VALUES
108On success, the
109.Fn kvm_getmaxcpu
110function returns the maximum number of CPUs supported by the kernel.
111If an error occurs,
112it returns -1 instead.
113.Pp
114On success, the
115.Fn kvm_getpcpu
116function returns a pointer to an allocated buffer or
117.Dv NULL .
118If an error occurs,
119it returns -1 instead.
120.Pp
121On success, the
122.Fn kvm_dpcpu_setcpu
123call returns 0; if an error occurs, it returns -1 instead.
124.Pp
| 112Symbols for dynamic per-CPU data are accessed via
113.Xr kvm_nlist 3
114as with other symbols.
115.Nm libkvm
116maintains a notion of the "current CPU", set by
117.Xr kvm_dpcpu_setcpu ,
118which defaults to 0.
119Once another CPU is selected,
120.Xr kvm_nlist 3
121will return pointers to that data on the appropriate CPU.
122.Sh CACHING
123.Fn kvm_getmaxcpu
124and
125.Fn kvm_getpcpu
126cache the nlist values for various kernel variables which are
127reused in successive calls.
128You may call either function with
129.Fa kd
130set to
131.Dv NULL
132to clear this cache.
133.Sh RETURN VALUES
134On success, the
135.Fn kvm_getmaxcpu
136function returns the maximum number of CPUs supported by the kernel.
137If an error occurs,
138it returns -1 instead.
139.Pp
140On success, the
141.Fn kvm_getpcpu
142function returns a pointer to an allocated buffer or
143.Dv NULL .
144If an error occurs,
145it returns -1 instead.
146.Pp
147On success, the
148.Fn kvm_dpcpu_setcpu
149call returns 0; if an error occurs, it returns -1 instead.
150.Pp
|
| 151On success, the
152.Fn kvm_read_zpcpu
153function returns number of bytes copied.
154If an error occurs, it returns -1 instead.
155.Pp
|
125If any function encounters an error,
126then an error message may be retrieved via
127.Xr kvm_geterr 3 .
128.Sh SEE ALSO
129.Xr free 3 ,
| 156If any function encounters an error,
157then an error message may be retrieved via
158.Xr kvm_geterr 3 .
159.Sh SEE ALSO
160.Xr free 3 ,
|
130.Xr kvm 3
| 161.Xr kvm 3 ,
162.Xr counter 9 ,
163.Xr zone 9
|
| |