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 <lttng/ringbuffer-config.h>
22 #include "../libringbuffer/getcpu.h"
25 size_t cpu_id_get_size(struct lttng_ctx_field
*field
, size_t offset
)
29 size
+= lib_ring_buffer_align(offset
, lttng_alignof(int));
35 void cpu_id_record(struct lttng_ctx_field
*field
,
36 struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
37 struct lttng_channel
*chan
)
41 cpu
= lttng_ust_get_cpu();
42 lib_ring_buffer_align_ctx(ctx
, lttng_alignof(cpu
));
43 chan
->ops
->event_write(ctx
, &cpu
, sizeof(cpu
));
47 void cpu_id_get_value(struct lttng_ctx_field
*field
,
48 struct lttng_ctx_value
*value
)
50 value
->u
.s64
= lttng_ust_get_cpu();
53 int lttng_add_cpu_id_to_ctx(struct lttng_ctx
**ctx
)
55 struct lttng_ctx_field
*field
;
57 field
= lttng_append_context(ctx
);
60 if (lttng_find_context(*ctx
, "cpu_id")) {
61 lttng_remove_context_field(ctx
, field
);
64 field
->event_field
.name
= "cpu_id";
65 field
->event_field
.type
.atype
= atype_integer
;
66 field
->event_field
.type
.u
.integer
.size
= sizeof(int) * CHAR_BIT
;
67 field
->event_field
.type
.u
.integer
.alignment
= lttng_alignof(int) * CHAR_BIT
;
68 field
->event_field
.type
.u
.integer
.signedness
= lttng_is_signed_type(int);
69 field
->event_field
.type
.u
.integer
.reverse_byte_order
= 0;
70 field
->event_field
.type
.u
.integer
.base
= 10;
71 field
->event_field
.type
.u
.integer
.encoding
= lttng_encode_none
;
72 field
->get_size
= cpu_id_get_size
;
73 field
->record
= cpu_id_record
;
74 field
->get_value
= cpu_id_get_value
;
75 lttng_context_update(*ctx
);