2 * lttng-context-cpu-id.c
4 * LTTng UST CPU id context.
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.
12 * Copyright (C) 2009-2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
30 #include <sys/types.h>
32 #include <lttng/ust-events.h>
33 #include <lttng/ust-tracer.h>
34 #include <lttng/ringbuffer-config.h>
35 #include "../libringbuffer/getcpu.h"
38 size_t cpu_id_get_size(struct lttng_ctx_field
*field
, size_t offset
)
42 size
+= lib_ring_buffer_align(offset
, lttng_alignof(int));
48 void cpu_id_record(struct lttng_ctx_field
*field
,
49 struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
50 struct lttng_channel
*chan
)
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
));
60 void cpu_id_get_value(struct lttng_ctx_field
*field
,
61 struct lttng_ctx_value
*value
)
65 cpu
= lttng_ust_get_cpu();
69 int lttng_add_cpu_id_to_ctx(struct lttng_ctx
**ctx
)
71 struct lttng_ctx_field
*field
;
73 field
= lttng_append_context(ctx
);
76 if (lttng_find_context(*ctx
, "cpu_id")) {
77 lttng_remove_context_field(ctx
, field
);
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
);