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1 | /* |
2 | * lttng-context-cpu-id.c | |
3 | * | |
4 | * LTTng UST CPU id context. | |
5 | * | |
6 | * Note: threads can be migrated at any point while executing the | |
7 | * tracepoint probe. This means the CPU id field (and filter) is only | |
8 | * statistical. For instance, even though a user might select a | |
9 | * cpu_id==1 filter, there may be few events recorded into the channel | |
10 | * appearing from other CPUs, due to migration. | |
11 | * | |
12 | * Copyright (C) 2009-2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
13 | * | |
14 | * This library is free software; you can redistribute it and/or | |
15 | * modify it under the terms of the GNU Lesser General Public | |
16 | * License as published by the Free Software Foundation; only | |
17 | * version 2.1 of the License. | |
18 | * | |
19 | * This library is distributed in the hope that it will be useful, | |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
22 | * Lesser General Public License for more details. | |
23 | * | |
24 | * You should have received a copy of the GNU Lesser General Public | |
25 | * License along with this library; if not, write to the Free Software | |
26 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
27 | */ | |
28 | ||
29 | #define _GNU_SOURCE | |
30 | #include <sys/types.h> | |
31 | #include <unistd.h> | |
32 | #include <lttng/ust-events.h> | |
33 | #include <lttng/ust-tracer.h> | |
34 | #include <lttng/ringbuffer-config.h> | |
35 | #include "../libringbuffer/getcpu.h" | |
36 | ||
37 | static | |
38 | size_t cpu_id_get_size(size_t offset) | |
39 | { | |
40 | size_t size = 0; | |
41 | ||
42 | size += lib_ring_buffer_align(offset, lttng_alignof(int)); | |
43 | size += sizeof(int); | |
44 | return size; | |
45 | } | |
46 | ||
47 | static | |
48 | void cpu_id_record(struct lttng_ctx_field *field, | |
49 | struct lttng_ust_lib_ring_buffer_ctx *ctx, | |
50 | struct lttng_channel *chan) | |
51 | { | |
52 | int cpu; | |
53 | ||
54 | cpu = lttng_ust_get_cpu(); | |
55 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(cpu)); | |
56 | chan->ops->event_write(ctx, &cpu, sizeof(cpu)); | |
57 | } | |
58 | ||
59 | static | |
60 | void cpu_id_get_value(struct lttng_ctx_field *field, | |
61 | union lttng_ctx_value *value) | |
62 | { | |
63 | int cpu; | |
64 | ||
65 | cpu = lttng_ust_get_cpu(); | |
66 | value->s64 = cpu; | |
67 | } | |
68 | ||
69 | int lttng_add_cpu_id_to_ctx(struct lttng_ctx **ctx) | |
70 | { | |
71 | struct lttng_ctx_field *field; | |
72 | ||
73 | field = lttng_append_context(ctx); | |
74 | if (!field) | |
75 | return -ENOMEM; | |
76 | if (lttng_find_context(*ctx, "cpu_id")) { | |
77 | lttng_remove_context_field(ctx, field); | |
78 | return -EEXIST; | |
79 | } | |
80 | field->event_field.name = "cpu_id"; | |
81 | field->event_field.type.atype = atype_integer; | |
82 | field->event_field.type.u.basic.integer.size = sizeof(int) * CHAR_BIT; | |
83 | field->event_field.type.u.basic.integer.alignment = lttng_alignof(int) * CHAR_BIT; | |
84 | field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(int); | |
85 | field->event_field.type.u.basic.integer.reverse_byte_order = 0; | |
86 | field->event_field.type.u.basic.integer.base = 10; | |
87 | field->event_field.type.u.basic.integer.encoding = lttng_encode_none; | |
88 | field->get_size = cpu_id_get_size; | |
89 | field->record = cpu_id_record; | |
90 | field->get_value = cpu_id_get_value; | |
91 | lttng_context_update(*ctx); | |
92 | return 0; | |
93 | } |