[PATCH 11/14] tools/perf: Process the DTL entries in queue and deliver samples
Athira Rajeev
atrajeev at linux.ibm.com
Fri Aug 15 18:34:04 AEST 2025
Create samples from DTL entries for displaying in perf report
and perf script. When the different PERF_RECORD_XX records are
processed from perf session, powerpc_vpadtl_process_event() will
be invoked. For each of the PERF_RECORD_XX record, compare the timestamp
of perf record with timestamp of top element in the auxtrace heap.
Process the auxtrace queue if the timestamp of element from heap is
lower than timestamp from entry in perf record.
Sometimes it could happen that one buffer is only partially
processed. if the timestamp of occurrence of another event is more
than currently processed element in the queue, it will move on
to next perf record. So keep track of position of buffer to
continue processing next time. Update the timestamp of the
auxtrace heap with the timestamp of last processed entry from
the auxtrace buffer.
Generate perf sample for each entry in the dispatch trace log.
Fill in the sample details:
- sample ip is picked from srr0 field of dtl_entry
- sample cpu is picked from processor_id of dtl_entry
- sample id is from sample_id of powerpc_vpadtl
- cpumode is set to PERF_RECORD_MISC_KERNEL
- Additionally save the details in raw_data of sample. This
is to print the relevant fields in perf_sample__fprintf_synth()
when called from builtin-script
The sample is processed by calling perf_session__deliver_synth_event()
so that it gets included in perf report.
Sample Output:
./perf record -a -e sched:*,vpa_dtl/dtl_all/ -c 1000000000 sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.300 MB perf.data ]
./perf report
# Samples: 321 of event 'vpa-dtl'
# Event count (approx.): 321
#
# Children Self Command Shared Object Symbol
# ........ ........ ....... ................. ..............................
#
100.00% 100.00% swapper [kernel.kallsyms] [k] plpar_hcall_norets_notrace
Signed-off-by: Athira Rajeev <atrajeev at linux.ibm.com>
---
tools/perf/util/powerpc-vpadtl.c | 181 +++++++++++++++++++++++++++++++
1 file changed, 181 insertions(+)
diff --git a/tools/perf/util/powerpc-vpadtl.c b/tools/perf/util/powerpc-vpadtl.c
index 299927901c9d..370c566f9ac2 100644
--- a/tools/perf/util/powerpc-vpadtl.c
+++ b/tools/perf/util/powerpc-vpadtl.c
@@ -160,6 +160,43 @@ static void powerpc_vpadtl_dump_event(struct powerpc_vpadtl *vpa, unsigned char
powerpc_vpadtl_dump(vpa, buf, len);
}
+/*
+ * Generate perf sample for each entry in the dispatch trace log.
+ * - sample ip is picked from srr0 field of dtl_entry
+ * - sample cpu is picked from logical cpu.
+ * - sample id is from sample_id of powerpc_vpadtl
+ * - cpumode is set to PERF_RECORD_MISC_KERNEL
+ * - Additionally save the details in raw_data of sample. This
+ * is to print the relevant fields in perf_sample__fprintf_synth()
+ * when called from builtin-script
+ */
+static int powerpc_vpadtl_sample(struct dtl_entry *record, struct powerpc_vpadtl *vpa, u64 save, int cpu)
+{
+ struct perf_sample sample;
+ union perf_event event;
+
+ sample.ip = be64_to_cpu(record->srr0);
+ sample.period = 1;
+ sample.cpu = cpu;
+ sample.id = vpa->sample_id;
+ sample.callchain = NULL;
+ sample.branch_stack = NULL;
+ memset(&event, 0, sizeof(event));
+ sample.cpumode = PERF_RECORD_MISC_KERNEL;
+ sample.time = save;
+ sample.raw_data = record;
+ sample.raw_size = sizeof(record);
+ event.sample.header.type = PERF_RECORD_SAMPLE;
+ event.sample.header.misc = sample.cpumode;
+ event.sample.header.size = sizeof(struct perf_event_header);
+ if (perf_session__deliver_synth_event(vpa->session, &event,
+ &sample)) {
+ pr_debug("Failed to create sample for dtl entry\n");
+ return -1;
+ }
+ return 0;
+}
+
static int powerpc_vpadtl_get_buffer(struct powerpc_vpadtl_queue *vpaq)
{
struct auxtrace_buffer *buffer = vpaq->buffer;
@@ -233,6 +270,148 @@ static int powerpc_vpadtl_decode(struct powerpc_vpadtl_queue *vpaq)
return 1;
}
+static int powerpc_vpadtl_decode_all(struct powerpc_vpadtl_queue *vpaq)
+{
+ int ret;
+ unsigned char *buf;
+
+ if (!vpaq->buf_len || (vpaq->pkt_len == vpaq->size)) {
+ ret = powerpc_vpadtl_get_buffer(vpaq);
+ if (ret <= 0)
+ return ret;
+ }
+
+ if (vpaq->buffer) {
+ buf = vpaq->buffer->data;
+ buf += vpaq->pkt_len;
+ vpaq->dtl = (struct dtl_entry *)buf;
+ if ((long long)be64_to_cpu(vpaq->dtl->timebase) <= 0) {
+ if (vpaq->pkt_len != dtl_entry_size && vpaq->buf_len) {
+ vpaq->pkt_len += dtl_entry_size;
+ vpaq->buf_len -= dtl_entry_size;
+ }
+ return -1;
+ }
+ vpaq->pkt_len += dtl_entry_size;
+ vpaq->buf_len -= dtl_entry_size;
+ } else
+ return 0;
+
+
+ return 1;
+}
+
+static int powerpc_vpadtl_run_decoder(struct powerpc_vpadtl_queue *vpaq, u64 *timestamp)
+{
+ struct powerpc_vpadtl *vpa = vpaq->vpa;
+ struct dtl_entry *record;
+ int ret;
+ double result, div;
+ double boot_freq = vpaq->tb_freq;
+ unsigned long long boot_tb = vpaq->boot_tb;
+ unsigned long long diff;
+ unsigned long long save;
+
+ while (1) {
+ ret = powerpc_vpadtl_decode_all(vpaq);
+ if (!ret) {
+ pr_debug("All data in the queue has been processed.\n");
+ return 1;
+ }
+
+ /*
+ * Error is detected when decoding VPA PMU trace. Continue to
+ * the next trace data and find out more dtl entries.
+ */
+ if (ret < 0)
+ continue;
+
+ record = vpaq->dtl;
+
+ diff = be64_to_cpu(record->timebase) - boot_tb;
+ div = diff / boot_freq;
+ result = div;
+ result = result * 1000000000;
+ save = result;
+
+ /* Update timestamp for the last record */
+ if (save > vpaq->timestamp)
+ vpaq->timestamp = save;
+
+ /*
+ * If the timestamp of the queue is later than timestamp of the
+ * coming perf event, bail out so can allow the perf event to
+ * be processed ahead.
+ */
+ if (vpaq->timestamp >= *timestamp) {
+ *timestamp = vpaq->timestamp;
+ vpaq->pkt_len -= dtl_entry_size;
+ vpaq->buf_len += dtl_entry_size;
+ return 0;
+ }
+
+ ret = powerpc_vpadtl_sample(record, vpa, save, vpaq->cpu);
+ if (ret)
+ continue;
+ }
+ return 0;
+}
+
+/*
+ * For each of the PERF_RECORD_XX record, compare the timestamp
+ * of perf record with timestamp of top element in the auxtrace heap.
+ * Process the auxtrace queue if the timestamp of element from heap is
+ * lower than timestamp from entry in perf record.
+ *
+ * Update the timestamp of the auxtrace heap with the timestamp
+ * of last processed entry from the auxtrace buffer.
+ */
+static int powerpc_vpadtl_process_queues(struct powerpc_vpadtl *vpa, u64 timestamp)
+{
+ unsigned int queue_nr;
+ u64 ts;
+ int ret;
+
+ while (1) {
+ struct auxtrace_queue *queue;
+ struct powerpc_vpadtl_queue *vpaq;
+
+ if (!vpa->heap.heap_cnt)
+ return 0;
+
+ if (vpa->heap.heap_array[0].ordinal >= timestamp)
+ return 0;
+
+ queue_nr = vpa->heap.heap_array[0].queue_nr;
+ queue = &vpa->queues.queue_array[queue_nr];
+ vpaq = queue->priv;
+
+ auxtrace_heap__pop(&vpa->heap);
+
+ if (vpa->heap.heap_cnt) {
+ ts = vpa->heap.heap_array[0].ordinal + 1;
+ if (ts > timestamp)
+ ts = timestamp;
+ } else
+ ts = timestamp;
+
+ ret = powerpc_vpadtl_run_decoder(vpaq, &ts);
+ if (ret < 0) {
+ auxtrace_heap__add(&vpa->heap, queue_nr, ts);
+ return ret;
+ }
+
+ if (!ret) {
+ ret = auxtrace_heap__add(&vpa->heap, queue_nr, ts);
+ if (ret < 0)
+ return ret;
+ } else {
+ vpaq->on_heap = false;
+ }
+ }
+ return 0;
+}
+
static struct powerpc_vpadtl_queue *powerpc_vpadtl__alloc_queue(struct powerpc_vpadtl *vpa,
unsigned int queue_nr)
{
@@ -368,6 +547,8 @@ static int powerpc_vpadtl_process_event(struct perf_session *session __maybe_unu
err = powerpc_vpadtl__update_queues(vpa);
if (err)
return err;
+
+ err = powerpc_vpadtl_process_queues(vpa, sample->time);
}
return err;
--
2.47.1
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