GSoC Project | Basic Support for Trace Compass

[Sebastian Huber]

On 24/07/2019 07:47, Ravindra Kumar Meena wrote:
>     This makes no sense:
> 
>     static void print_item( client_context *cctx, const client_item *item )
>     {
>         if( cctx->event_counter % 2 == 0 ){
> 
>     1. event_counter is not per CPU.
> 
>     2. You don't care about the record event. You have to do this for
>     specific events as I already wrote in the description of this task.
> 
> 
> I forgot to remove the modular operator.
> 
> https://github.com/rmeena840/rtems-tools/commit/c278c48abab1d5ea93cf36823bd24af07633f35f
> 
> The logic behind this is that when the first time program enters in 
> print_item() it initializes the
> prev_* values and after this, it will enter in else part recursively 
> initializing prev_* and next_* values for the same CPU and write it in 
> the file.

This approach makes no sense to me.

Per CPU you receive three record events in succession:

[19:32:26.679099590] (+0.000046608) Record_Item RTEMS_RECORDING_EVENT: { 
cpu_id = 5 }, { event = ( "RTEMS_RECORD_THREAD_SWITCH_OUT" : container = 
216 ), data = 167837707 }
[19:32:26.679099590] (+0.000000000) Record_Item RTEMS_RECORDING_EVENT: { 
cpu_id = 5 }, { event = ( "RTEMS_RECORD_THREAD_STACK_CURRENT" : 
container = 209 ), data = 32320 }
[19:32:26.679099590] (+0.000000000) Record_Item RTEMS_RECORDING_EVENT: { 
cpu_id = 5 }, { event = ( "RTEMS_RECORD_THREAD_SWITCH_IN" : container = 
215 ), data = 151060501 }

They have all the same timestamp.

When you receive an RTEMS_RECORD_THREAD_SWITCH_OUT event, you store the 
timestamp (per CPU) and the data (per-CPU, this is the thread ID).

When you receive an RTEMS_RECORD_THREAD_SWITCH_IN event and the 
timestamp matches, you use the values of the current event and the 
values stored before to output an LTTNG sched_switch event.

-- 
Sebastian Huber, embedded brains GmbH

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