Re: [PATCH v2 01/18] perf cs-etm: Queue context packets for frontend

On Tue, Jun 02, 2026 at 03:26:43PM +0100, James Clark wrote:

[...]

@@ -614,10 +621,12 @@ static int cs_etm__init_traceid_queue(struct cs_etm_queue *etmq, queue = &etmq->etm->queues.queue_array[etmq->queue_nr]; tidq->trace_chan_id = trace_chan_id;

• tidq->el = tidq->prev_packet_el = ocsd_EL_unknown;
• tidq->thread = machine__findnew_thread(&etm->session->machines.host, -1,

• tidq->decode_el = ocsd_EL_unknown;
• tidq->frontend_thread = machine__findnew_thread(&etm->session->machines.host, -1,

• 			       queue->tid);
  

• tidq->decode_thread = machine__findnew_thread(&etm->session->machines.host, -1, queue->tid);

• tidq->prev_packet_thread = machine__idle_thread(&etm->session->machines.host);

Redundant new line.

tidq->packet = zalloc(sizeof(struct cs_etm_packet)); if (!tidq->packet) @@ -751,20 +760,16 @@ static void cs_etm__packet_swap(struct cs_etm_auxtrace *etm, * Swap PACKET with PREV_PACKET: PACKET becomes PREV_PACKET for * the next incoming packet. *

•  * Threads and exception levels are also tracked for both the
  

•  * previous and current packets. This is because the previous
  

•  * packet is used for the 'from' IP for branch samples, so the
  

•  * thread at that time must also be assigned to that sample.
  

•  * Across discontinuity packets the thread can change, so by
  

•  * tracking the thread for the previous packet the branch sample
  

•  * will have the correct info.
  

•  * Track Exception levels for both the previous and current
  

•  * packets. This is because the previous packet's address is
  

•  * used for the 'from' IP for branch samples, so the previous EL
  

•  * must also be used so that sample shows it originates from the
  

•  * correct EL. Branches can't branch to a different thread, so
  

•  * no need to track the previous thread.
  

  */ tmp = tidq->packet; tidq->packet = tidq->prev_packet; tidq->prev_packet = tmp;

• tidq->prev_packet_el = tidq->el;
  

• thread__put(tidq->prev_packet_thread);
  

• tidq->prev_packet_thread = thread__get(tidq->thread);
  

As here no any code for EL swap, the comment above is a bit disconnected with the code. Can we just remove the comment to avoid confusion?

Otherwise, looks good. Thanks for maturing the patch.

Leo