2 * SPDX-License-Identifier: LGPL-2.1-only
4 * Copyright (C) 2009-2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * LTTng UST CPU id context.
8 * Note: threads can be migrated at any point while executing the
9 * tracepoint probe. This means the CPU id field (and filter) is only
10 * statistical. For instance, even though a user might select a
11 * cpu_id==1 filter, there may be few events recorded into the channel
12 * appearing from other CPUs, due to migration.
17 #include <sys/types.h>
19 #include <lttng/ust-events.h>
20 #include <lttng/ust-tracer.h>
21 #include "../libringbuffer/getcpu.h"
22 #include <lttng/ringbuffer-context.h>
24 #include "context-internal.h"
27 size_t cpu_id_get_size(struct lttng_ust_ctx_field
*field
, size_t offset
)
31 size
+= lib_ring_buffer_align(offset
, lttng_alignof(int));
37 void cpu_id_record(struct lttng_ust_ctx_field
*field
,
38 struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
39 struct lttng_ust_channel_buffer
*chan
)
43 cpu
= lttng_ust_get_cpu();
44 lib_ring_buffer_align_ctx(ctx
, lttng_alignof(cpu
));
45 chan
->ops
->event_write(ctx
, &cpu
, sizeof(cpu
));
49 void cpu_id_get_value(struct lttng_ust_ctx_field
*field
,
50 struct lttng_ust_ctx_value
*value
)
52 value
->u
.s64
= lttng_ust_get_cpu();
55 int lttng_add_cpu_id_to_ctx(struct lttng_ust_ctx
**ctx
)
57 struct lttng_ust_ctx_field
*field
;
58 struct lttng_ust_type_common
*type
;
61 type
= lttng_ust_create_type_integer(sizeof(int) * CHAR_BIT
,
62 lttng_alignof(int) * CHAR_BIT
,
63 lttng_is_signed_type(int),
67 field
= lttng_append_context(ctx
);
72 if (lttng_find_context(*ctx
, "cpu_id")) {
74 goto error_find_context
;
76 field
->event_field
->name
= strdup("cpu_id");
77 if (!field
->event_field
->name
) {
81 field
->event_field
->type
= type
;
82 field
->get_size
= cpu_id_get_size
;
83 field
->record
= cpu_id_record
;
84 field
->get_value
= cpu_id_get_value
;
85 lttng_context_update(*ctx
);
90 lttng_remove_context_field(ctx
, field
);
92 lttng_ust_destroy_type(type
);