| Modifications in the patch resolving conflicts: |
| - perf_record_aux renamed to aux_event; |
| - perf_record_auxtrace renamed to auxtrace_event; |
| - evlist__event2evsel renamed to perf_evlist__event2evsel; |
| - evsel__parse_sample renamed to perf_evsel__parse_sample; |
| - Replace "PRI_lx64 with l"PRIx64. |
| |
| From a05337312ae7f16c15b01ce77c85232f6a3dca1d Mon Sep 17 00:00:00 2001 |
| From: James Clark <james.clark@arm.com> |
| Date: Thu, 24 Jun 2021 17:43:02 +0100 |
| Subject: [PATCH] perf cs-etm: Split Coresight decode by aux records |
| |
| Populate the auxtrace queues using AUX records rather than whole |
| auxtrace buffers so that the decoder is reset between each aux record. |
| |
| This is similar to the auxtrace_queues__process_index() -> |
| auxtrace_queues__add_indexed_event() flow where |
| perf_session__peek_event() is used to read AUXTRACE events out of random |
| positions in the file based on the auxtrace index. |
| |
| But now we loop over all PERF_RECORD_AUX events instead of AUXTRACE |
| buffers. For each PERF_RECORD_AUX event, we find the corresponding |
| AUXTRACE buffer using the index, and add a fragment of that buffer to |
| the auxtrace queues. |
| |
| No other changes to decoding were made, apart from populating the |
| auxtrace queues. The result of decoding is identical to before, except |
| in cases where decoding failed completely, due to not resetting the |
| decoder. |
| |
| The reason for this change is because AUX records are emitted any time |
| tracing is disabled, for example when the process is scheduled out. |
| Because ETM was disabled and enabled again, the decoder also needs to be |
| reset to force the search for a sync packet. Otherwise there would be |
| fatal decoding errors. |
| |
| Testing |
| ======= |
| |
| Testing was done with the following script, to diff the decoding results |
| between the patched and un-patched versions of perf: |
| |
| #!/bin/bash |
| set -ex |
| |
| $1 script -i $3 $4 > split.script |
| $2 script -i $3 $4 > default.script |
| |
| diff split.script default.script | head -n 20 |
| |
| And it was run like this, with various itrace options depending on the |
| quantity of synthesised events: |
| |
| compare.sh ./perf-patched ./perf-default perf-per-cpu-2-threads.data --itrace=i100000ns |
| |
| No changes in output were observed in the following scenarios: |
| |
| * Simple per-cpu |
| perf record -e cs_etm/@tmc_etr0/u top |
| |
| * Per-thread, single thread |
| perf record -e cs_etm/@tmc_etr0/u --per-thread ./threads_C |
| |
| * Per-thread multiple threads (but only one thread collected data): |
| perf record -e cs_etm/@tmc_etr0/u --per-thread --pid 4596,4597 |
| |
| * Per-thread multiple threads (both threads collected data): |
| perf record -e cs_etm/@tmc_etr0/u --per-thread --pid 4596,4597 |
| |
| * Per-cpu explicit threads: |
| perf record -e cs_etm/@tmc_etr0/u --pid 853,854 |
| |
| * System-wide (per-cpu): |
| perf record -e cs_etm/@tmc_etr0/u -a |
| |
| * No data collected (no aux buffers) |
| Can happen with any command when run for a short period |
| |
| * Containing truncated records |
| Can happen with any command |
| |
| * Containing aux records with 0 size |
| Can happen with any command |
| |
| * Snapshot mode (various files with and without buffer wrap) |
| perf record -e cs_etm/@tmc_etr0/u -a --snapshot |
| |
| Some differences were observed in the following scenario: |
| |
| * Snapshot mode (with duplicate buffers) |
| perf record -e cs_etm/@tmc_etr0/u -a --snapshot |
| |
| Fewer samples are generated in snapshot mode if duplicate buffers |
| were gathered because buffers with the same offset are now only added |
| once. This gives different, but more correct results and no duplicate |
| data is decoded any more. |
| |
| Signed-off-by: James Clark <james.clark@arm.com> |
| Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> |
| Tested-by: Leo Yan <leo.yan@linaro.org> |
| Cc: Al Grant <al.grant@arm.com> |
| Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> |
| Cc: Anshuman Khandual <anshuman.khandual@arm.com> |
| Cc: Branislav Rankov <branislav.rankov@arm.com> |
| Cc: Denis Nikitin <denik@chromium.org> |
| Cc: Jiri Olsa <jolsa@redhat.com> |
| Cc: John Garry <john.garry@huawei.com> |
| Cc: Mark Rutland <mark.rutland@arm.com> |
| Cc: Mike Leach <mike.leach@linaro.org> |
| Cc: Namhyung Kim <namhyung@kernel.org> |
| Cc: Suzuki Poulouse <suzuki.poulose@arm.com> |
| Cc: Will Deacon <will@kernel.org> |
| Cc: coresight@lists.linaro.org |
| Cc: linux-arm-kernel@lists.infradead.org |
| Link: http://lore.kernel.org/lkml/20210624164303.28632-2-james.clark@arm.com |
| Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
| --- |
| tools/perf/util/cs-etm.c | 168 ++++++++++++++++++++++++++++++++++++++- |
| 1 file changed, 167 insertions(+), 1 deletion(-) |
| |
| diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c |
| index 5095c1c4c6df..a57fabee6d53 100644 |
| --- a/tools/perf/util/cs-etm.c |
| +++ b/tools/perf/util/cs-etm.c |
| @@ -2620,6 +2620,172 @@ static u64 *cs_etm__create_meta_blk(u64 *buff_in, int *buff_in_offset, |
| return metadata; |
| } |
| |
| +/** |
| + * Puts a fragment of an auxtrace buffer into the auxtrace queues based |
| + * on the bounds of aux_event, if it matches with the buffer that's at |
| + * file_offset. |
| + * |
| + * Normally, whole auxtrace buffers would be added to the queue. But we |
| + * want to reset the decoder for every PERF_RECORD_AUX event, and the decoder |
| + * is reset across each buffer, so splitting the buffers up in advance has |
| + * the same effect. |
| + */ |
| +static int cs_etm__queue_aux_fragment(struct perf_session *session, off_t file_offset, size_t sz, |
| + struct aux_event *aux_event, struct perf_sample *sample) |
| +{ |
| + int err; |
| + char buf[PERF_SAMPLE_MAX_SIZE]; |
| + union perf_event *auxtrace_event_union; |
| + struct auxtrace_event *auxtrace_event; |
| + union perf_event auxtrace_fragment; |
| + __u64 aux_offset, aux_size; |
| + |
| + struct cs_etm_auxtrace *etm = container_of(session->auxtrace, |
| + struct cs_etm_auxtrace, |
| + auxtrace); |
| + |
| + /* |
| + * There should be a PERF_RECORD_AUXTRACE event at the file_offset that we got |
| + * from looping through the auxtrace index. |
| + */ |
| + err = perf_session__peek_event(session, file_offset, buf, |
| + PERF_SAMPLE_MAX_SIZE, &auxtrace_event_union, NULL); |
| + if (err) |
| + return err; |
| + auxtrace_event = &auxtrace_event_union->auxtrace; |
| + if (auxtrace_event->header.type != PERF_RECORD_AUXTRACE) |
| + return -EINVAL; |
| + |
| + if (auxtrace_event->header.size < sizeof(struct auxtrace_event) || |
| + auxtrace_event->header.size != sz) { |
| + return -EINVAL; |
| + } |
| + |
| + /* |
| + * In per-thread mode, CPU is set to -1, but TID will be set instead. See |
| + * auxtrace_mmap_params__set_idx(). Return 'not found' if neither CPU nor TID match. |
| + */ |
| + if ((auxtrace_event->cpu == (__u32) -1 && auxtrace_event->tid != sample->tid) || |
| + auxtrace_event->cpu != sample->cpu) |
| + return 1; |
| + |
| + if (aux_event->flags & PERF_AUX_FLAG_OVERWRITE) { |
| + /* |
| + * Clamp size in snapshot mode. The buffer size is clamped in |
| + * __auxtrace_mmap__read() for snapshots, so the aux record size doesn't reflect |
| + * the buffer size. |
| + */ |
| + aux_size = min(aux_event->aux_size, auxtrace_event->size); |
| + |
| + /* |
| + * In this mode, the head also points to the end of the buffer so aux_offset |
| + * needs to have the size subtracted so it points to the beginning as in normal mode |
| + */ |
| + aux_offset = aux_event->aux_offset - aux_size; |
| + } else { |
| + aux_size = aux_event->aux_size; |
| + aux_offset = aux_event->aux_offset; |
| + } |
| + |
| + if (aux_offset >= auxtrace_event->offset && |
| + aux_offset + aux_size <= auxtrace_event->offset + auxtrace_event->size) { |
| + /* |
| + * If this AUX event was inside this buffer somewhere, create a new auxtrace event |
| + * based on the sizes of the aux event, and queue that fragment. |
| + */ |
| + auxtrace_fragment.auxtrace = *auxtrace_event; |
| + auxtrace_fragment.auxtrace.size = aux_size; |
| + auxtrace_fragment.auxtrace.offset = aux_offset; |
| + file_offset += aux_offset - auxtrace_event->offset + auxtrace_event->header.size; |
| + |
| + pr_debug3("CS ETM: Queue buffer size: %#l"PRIx64" offset: %#l"PRIx64 |
| + " tid: %d cpu: %d\n", aux_size, aux_offset, sample->tid, sample->cpu); |
| + return auxtrace_queues__add_event(&etm->queues, session, &auxtrace_fragment, |
| + file_offset, NULL); |
| + } |
| + |
| + /* Wasn't inside this buffer, but there were no parse errors. 1 == 'not found' */ |
| + return 1; |
| +} |
| + |
| +static int cs_etm__queue_aux_records_cb(struct perf_session *session, union perf_event *event, |
| + u64 offset __maybe_unused, void *data __maybe_unused) |
| +{ |
| + struct perf_sample sample; |
| + int ret; |
| + struct auxtrace_index_entry *ent; |
| + struct auxtrace_index *auxtrace_index; |
| + struct evsel *evsel; |
| + size_t i; |
| + |
| + /* Don't care about any other events, we're only queuing buffers for AUX events */ |
| + if (event->header.type != PERF_RECORD_AUX) |
| + return 0; |
| + |
| + if (event->header.size < sizeof(struct aux_event)) |
| + return -EINVAL; |
| + |
| + /* Truncated Aux records can have 0 size and shouldn't result in anything being queued. */ |
| + if (!event->aux.aux_size) |
| + return 0; |
| + |
| + /* |
| + * Parse the sample, we need the sample_id_all data that comes after the event so that the |
| + * CPU or PID can be matched to an AUXTRACE buffer's CPU or PID. |
| + */ |
| + evsel = perf_evlist__event2evsel(session->evlist, event); |
| + if (!evsel) |
| + return -EINVAL; |
| + ret = perf_evsel__parse_sample(evsel, event, &sample); |
| + if (ret) |
| + return ret; |
| + |
| + /* |
| + * Loop through the auxtrace index to find the buffer that matches up with this aux event. |
| + */ |
| + list_for_each_entry(auxtrace_index, &session->auxtrace_index, list) { |
| + for (i = 0; i < auxtrace_index->nr; i++) { |
| + ent = &auxtrace_index->entries[i]; |
| + ret = cs_etm__queue_aux_fragment(session, ent->file_offset, |
| + ent->sz, &event->aux, &sample); |
| + /* |
| + * Stop search on error or successful values. Continue search on |
| + * 1 ('not found') |
| + */ |
| + if (ret != 1) |
| + return ret; |
| + } |
| + } |
| + |
| + /* |
| + * Couldn't find the buffer corresponding to this aux record, something went wrong. Warn but |
| + * don't exit with an error because it will still be possible to decode other aux records. |
| + */ |
| + pr_err("CS ETM: Couldn't find auxtrace buffer for aux_offset: %#l"PRIx64 |
| + " tid: %d cpu: %d\n", event->aux.aux_offset, sample.tid, sample.cpu); |
| + return 0; |
| +} |
| + |
| +static int cs_etm__queue_aux_records(struct perf_session *session) |
| +{ |
| + struct auxtrace_index *index = list_first_entry_or_null(&session->auxtrace_index, |
| + struct auxtrace_index, list); |
| + if (index && index->nr > 0) |
| + return perf_session__peek_events(session, session->header.data_offset, |
| + session->header.data_size, |
| + cs_etm__queue_aux_records_cb, NULL); |
| + |
| + /* |
| + * We would get here if there are no entries in the index (either no auxtrace |
| + * buffers or no index at all). Fail silently as there is the possibility of |
| + * queueing them in cs_etm__process_auxtrace_event() if etm->data_queued is still |
| + * false. |
| + * |
| + * In that scenario, buffers will not be split by AUX records. |
| + */ |
| + return 0; |
| +} |
| + |
| int cs_etm__process_auxtrace_info(union perf_event *event, |
| struct perf_session *session) |
| { |
| @@ -2819,7 +2985,7 @@ int cs_etm__process_auxtrace_info(union perf_event *event, |
| if (err) |
| goto err_delete_thread; |
| |
| - err = auxtrace_queues__process_index(&etm->queues, session); |
| + err = cs_etm__queue_aux_records(session); |
| if (err) |
| goto err_delete_thread; |
| |
| -- |
| 2.33.0.rc1.237.g0d66db33f3-goog |
| |