Re: [RFC PATCH v2 1/1] perf cs-etm: Set time value for samples

Hi Wojciech,

On Tue, May 28, 2019 at 06:18:50PM +0000, Wojciech Żmuda wrote:

From: Wojciech Zmuda wzmuda@n7space.com

Populate the 'time' field in branches and instruction samples generated from range and discontinuity packets. The time value is based on timestamp packets that may appear in the trace.

The time value may be accessed through perf-script built-in script engine in the sample dict 'time' field or printed in 'perf script -F time' output (the latter only in CPU-wide mode at the moment).

Did checkpatch return any errors on your side?

Signed-off-by: Wojciech Zmuda wzmuda@n7space.com

tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 70 ++++++++++++++++++++----- tools/perf/util/cs-etm.c | 3 ++ tools/perf/util/cs-etm.h | 1 + 3 files changed, 61 insertions(+), 13 deletions(-)

diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c index 33e975c8d11b..9263c803487f 100644 --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c @@ -269,10 +269,39 @@ cs_etm_decoder__create_etm_packet_printer(struct cs_etm_trace_params *t_params, trace_config); } +static void +cs_etm_decoder__timestamp_pending_packets(struct cs_etm_packet_queue *packet_queue) +{

• u32 count, head;
• struct cs_etm_packet *packet, *prev_packet;
• count = packet_queue->packet_count;
• if (count == 0)

• return;
  

• prev_packet = NULL;
• head = packet_queue->head;
• while (count--) {

• head = (head + 1) & (CS_ETM_PACKET_MAX_BUFFER - 1);
  

• packet = &packet_queue->packet_buffer[head];
  

• if (packet->sample_type != CS_ETM_RANGE &&
  

•     packet->sample_type != CS_ETM_DISCONTINUITY)
  

I don't think we should care about discontinuity packets if we haven't received a timestamp since the timestamp we just received is for range packets that appeared after the discontinuity.

• 	continue;
  

• /* TODO: find better approximation of the number of instructions per cycle. */
  

• if (!prev_packet)
  

• 	packet->timestamp = packet_queue->timestamp;
  

• else
  

• 	packet->timestamp = prev_packet->timestamp + prev_packet->instr_count;
  

• prev_packet = packet;
  

• }

+}

static ocsd_datapath_resp_t -cs_etm_decoder__do_soft_timestamp(struct cs_etm_queue *etmq,

• 		  struct cs_etm_packet_queue *packet_queue,
  

• 		  const uint8_t trace_chan_id)
  

+cs_etm_decoder__do_soft_timestamp(struct cs_etm_packet_queue *packet_queue) { /* No timestamp packet has been received, nothing to do */ if (!packet_queue->timestamp) @@ -284,9 +313,6 @@ cs_etm_decoder__do_soft_timestamp(struct cs_etm_queue *etmq, packet_queue->next_timestamp += packet_queue->instr_count; packet_queue->instr_count = 0;

• /* Tell the front end which traceid_queue needs attention */
• cs_etm__etmq_set_traceid_queue_timestamp(etmq, trace_chan_id);
• return OCSD_RESP_WAIT;

The new cs_etm_decoder__do_soft_timestamp() should only concern itself with setting the timestamp for the packet queue and let the calling code deal with everything else. As such the return type should be a "void". More on that below.

} @@ -324,6 +350,9 @@ cs_etm_decoder__do_hard_timestamp(struct cs_etm_queue *etmq, packet_queue->next_timestamp = elem->timestamp; packet_queue->instr_count = 0;

• /* Timestamp range packets that got queued up to this point */
• cs_etm_decoder__timestamp_pending_packets(packet_queue);
• /* Tell the front end which traceid_queue needs attention */ cs_etm__etmq_set_traceid_queue_timestamp(etmq, trace_chan_id);

@@ -372,6 +401,7 @@ cs_etm_decoder__buffer_packet(struct cs_etm_packet_queue *packet_queue, packet_queue->packet_buffer[et].flags = 0; packet_queue->packet_buffer[et].exception_number = UINT32_MAX; packet_queue->packet_buffer[et].trace_chan_id = trace_chan_id;

• packet_queue->packet_buffer[et].timestamp = 0;

if (packet_queue->packet_count == CS_ETM_PACKET_MAX_BUFFER - 1) return OCSD_RESP_WAIT; @@ -436,10 +466,6 @@ cs_etm_decoder__buffer_range(struct cs_etm_queue *etmq, packet->last_instr_size = elem->last_instr_sz;

Function cs_etm_decoder__do_soft_timestamp() (along with timestamping the packet) should be done right here. That way we can still get a timestamp for the packet even if the packet queue is full.

• /* per-thread scenario, no need to generate a timestamp */
• if (cs_etm__etmq_is_timeless(etmq))

• goto out;
  

• /*
  • The packet queue is full and we haven't seen a timestamp (had we
  • seen one the packet queue wouldn't be full). Let the front end

@@ -449,9 +475,14 @@ cs_etm_decoder__buffer_range(struct cs_etm_queue *etmq, goto out; packet_queue->instr_count += elem->num_instr_range;

• ret = cs_etm_decoder__do_soft_timestamp(packet_queue);
• if (ret == OCSD_RESP_CONT)

• goto out;
  

• /* Tell the front end we have a new timestamp to process */

• ret = cs_etm_decoder__do_soft_timestamp(etmq, packet_queue,

• 				trace_chan_id);
  

• packet->timestamp = packet_queue->timestamp;
• if (!cs_etm__etmq_is_timeless(etmq))

• cs_etm__etmq_set_traceid_queue_timestamp(etmq, trace_chan_id);
  

out: return ret; } @@ -460,13 +491,26 @@ static ocsd_datapath_resp_t cs_etm_decoder__buffer_discontinuity(struct cs_etm_packet_queue *queue, const uint8_t trace_chan_id) {

• int ret;
• struct cs_etm_packet *packet;
• u64 timestamp;
• /*
  • Something happened and who knows when we'll get new traces so
  • reset time statistics.

• * Record the last observed timestamp, so the last branch sample
  

• * before discontinuity can be marked with it.
  

  */
• timestamp = queue->timestamp; cs_etm_decoder__reset_timestamp(queue);

If you move this below "packet->timestamp = timestamp;", along with the comment, it won't be necessary to declare a new variable.

Thanks, Mathieu

• return cs_etm_decoder__buffer_packet(queue, trace_chan_id,

• ret = cs_etm_decoder__buffer_packet(queue, trace_chan_id, CS_ETM_DISCONTINUITY);
• packet = &queue->packet_buffer[queue->tail];
• packet->timestamp = timestamp;
• return ret;

} static ocsd_datapath_resp_t diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c index 8496190ad553..84d615ae3a1a 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c @@ -204,6 +204,7 @@ static void cs_etm__clear_packet_queue(struct cs_etm_packet_queue *queue) queue->packet_buffer[i].exception_number = UINT32_MAX; queue->packet_buffer[i].trace_chan_id = UINT8_MAX; queue->packet_buffer[i].cpu = INT_MIN;

• queue->packet_buffer[i].timestamp = 0;
  

  }

} @@ -1098,6 +1099,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq, sample.flags = tidq->prev_packet->flags; sample.insn_len = 1; sample.cpumode = event->sample.header.misc;

• sample.time = tidq->packet->timestamp;

if (etm->synth_opts.last_branch) { cs_etm__copy_last_branch_rb(etmq, tidq); @@ -1157,6 +1159,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq, sample.cpu = tidq->packet->cpu; sample.flags = tidq->prev_packet->flags; sample.cpumode = event->sample.header.misc;

• sample.time = tidq->packet->timestamp;

/* * perf report cannot handle events without a branch stack diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h index 1f6ec7babe70..a14b0220eaa7 100644 --- a/tools/perf/util/cs-etm.h +++ b/tools/perf/util/cs-etm.h @@ -122,6 +122,7 @@ struct cs_etm_packet { enum cs_etm_isa isa; u64 start_addr; u64 end_addr;

• u64 timestamp; u32 instr_count; u32 last_instr_type; u32 last_instr_subtype;

-- 2.11.0