On 15/09/2025 10:27, Athira Rajeev wrote:
> 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 <atraj...@linux.ibm.com>
> ---
> Changelog:
> Addressed review comments from Adrian:
> - Moved time calculation to different function
> - Alignment and wording changes
>
> tools/perf/util/powerpc-vpadtl.c | 173 +++++++++++++++++++++++++++++++
> 1 file changed, 173 insertions(+)
>
> diff --git a/tools/perf/util/powerpc-vpadtl.c
> b/tools/perf/util/powerpc-vpadtl.c
> index 637abde60f44..dc437dae16b8 100644
> --- a/tools/perf/util/powerpc-vpadtl.c
> +++ b/tools/perf/util/powerpc-vpadtl.c
> @@ -161,6 +161,43 @@ 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 powerpc_vpadtl_entry
> + * - sample cpu is logical cpu.
> + * - 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 powerpc_vpadtl_entry *record, struct
> powerpc_vpadtl *vpa, u64 save, int cpu)
line length of 116 exceeds 100 columns
> +{
> + 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;
> @@ -234,6 +271,140 @@ 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 powerpc_vpadtl_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 powerpc_vpadtl_entry *record;
> + int ret;
> + unsigned long long vpaq_timestamp;
> +
> + 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;
> +
> + vpaq_timestamp = powerpc_vpadtl_timestamp(vpaq);
> +
> + /* Update timestamp for the last record */
> + if (vpaq_timestamp > vpaq->timestamp)
> + vpaq->timestamp = vpaq_timestamp;
> +
> + /*
> + * 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, vpaq_timestamp,
> 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;
braces {} should be used on all arms of this statement
> +
> + 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)
> {
> @@ -347,6 +518,8 @@ 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;
