From ff3d527cebc1fa3707c617bfe9e74f53fcfb0955 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Tue, 27 Aug 2013 11:23:07 +0300 Subject: perf: make events stream always parsable The event stream is not always parsable because the format of a sample is dependent on the sample_type of the selected event. When there is more than one selected event and the sample_types are not the same then parsing becomes problematic. A sample can be matched to its selected event using the ID that is allocated when the event is opened. Unfortunately, to get the ID from the sample means first parsing it. This patch adds a new sample format bit PERF_SAMPLE_IDENTIFER that puts the ID at a fixed position so that the ID can be retrieved without parsing the sample. For sample events, that is the first position immediately after the header. For non-sample events, that is the last position. In this respect parsing samples requires that the sample_type and ID values are recorded. For example, perf tools records struct perf_event_attr and the IDs within the perf.data file. Those must be read first before it is possible to parse samples found later in the perf.data file. Signed-off-by: Adrian Hunter Tested-by: Stephane Eranian Acked-by: Peter Zijlstra Cc: David Ahern Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jiri Olsa Cc: Mike Galbraith Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1377591794-30553-6-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- include/uapi/linux/perf_event.h | 27 ++++++++++++++++++++------- kernel/events/core.c | 11 ++++++++++- 2 files changed, 30 insertions(+), 8 deletions(-) diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 62c25a2..42cb7b6 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -134,8 +134,9 @@ enum perf_event_sample_format { PERF_SAMPLE_STACK_USER = 1U << 13, PERF_SAMPLE_WEIGHT = 1U << 14, PERF_SAMPLE_DATA_SRC = 1U << 15, + PERF_SAMPLE_IDENTIFIER = 1U << 16, - PERF_SAMPLE_MAX = 1U << 16, /* non-ABI */ + PERF_SAMPLE_MAX = 1U << 17, /* non-ABI */ }; /* @@ -492,12 +493,12 @@ enum perf_event_type { /* * If perf_event_attr.sample_id_all is set then all event types will * have the sample_type selected fields related to where/when - * (identity) an event took place (TID, TIME, ID, CPU, STREAM_ID) - * described in PERF_RECORD_SAMPLE below, it will be stashed just after - * the perf_event_header and the fields already present for the existing - * fields, i.e. at the end of the payload. That way a newer perf.data - * file will be supported by older perf tools, with these new optional - * fields being ignored. + * (identity) an event took place (TID, TIME, ID, STREAM_ID, CPU, + * IDENTIFIER) described in PERF_RECORD_SAMPLE below, it will be stashed + * just after the perf_event_header and the fields already present for + * the existing fields, i.e. at the end of the payload. That way a newer + * perf.data file will be supported by older perf tools, with these new + * optional fields being ignored. * * struct sample_id { * { u32 pid, tid; } && PERF_SAMPLE_TID @@ -505,7 +506,12 @@ enum perf_event_type { * { u64 id; } && PERF_SAMPLE_ID * { u64 stream_id;} && PERF_SAMPLE_STREAM_ID * { u32 cpu, res; } && PERF_SAMPLE_CPU + * { u64 id; } && PERF_SAMPLE_IDENTIFIER * } && perf_event_attr::sample_id_all + * + * Note that PERF_SAMPLE_IDENTIFIER duplicates PERF_SAMPLE_ID. The + * advantage of PERF_SAMPLE_IDENTIFIER is that its position is fixed + * relative to header.size. */ /* @@ -594,6 +600,13 @@ enum perf_event_type { * struct { * struct perf_event_header header; * + * # + * # Note that PERF_SAMPLE_IDENTIFIER duplicates PERF_SAMPLE_ID. + * # The advantage of PERF_SAMPLE_IDENTIFIER is that its position + * # is fixed relative to header. + * # + * + * { u64 id; } && PERF_SAMPLE_IDENTIFIER * { u64 ip; } && PERF_SAMPLE_IP * { u32 pid, tid; } && PERF_SAMPLE_TID * { u64 time; } && PERF_SAMPLE_TIME diff --git a/kernel/events/core.c b/kernel/events/core.c index 928fae7..15d0f24 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1213,6 +1213,9 @@ static void perf_event__id_header_size(struct perf_event *event) if (sample_type & PERF_SAMPLE_TIME) size += sizeof(data->time); + if (sample_type & PERF_SAMPLE_IDENTIFIER) + size += sizeof(data->id); + if (sample_type & PERF_SAMPLE_ID) size += sizeof(data->id); @@ -4280,7 +4283,7 @@ static void __perf_event_header__init_id(struct perf_event_header *header, if (sample_type & PERF_SAMPLE_TIME) data->time = perf_clock(); - if (sample_type & PERF_SAMPLE_ID) + if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER)) data->id = primary_event_id(event); if (sample_type & PERF_SAMPLE_STREAM_ID) @@ -4319,6 +4322,9 @@ static void __perf_event__output_id_sample(struct perf_output_handle *handle, if (sample_type & PERF_SAMPLE_CPU) perf_output_put(handle, data->cpu_entry); + + if (sample_type & PERF_SAMPLE_IDENTIFIER) + perf_output_put(handle, data->id); } void perf_event__output_id_sample(struct perf_event *event, @@ -4432,6 +4438,9 @@ void perf_output_sample(struct perf_output_handle *handle, perf_output_put(handle, *header); + if (sample_type & PERF_SAMPLE_IDENTIFIER) + perf_output_put(handle, data->id); + if (sample_type & PERF_SAMPLE_IP) perf_output_put(handle, data->ip); -- cgit v1.1