Re: [PATCH v3 07/10] drm/msm/A6xx: Add traces for preemption

[Antonino Maniscalco <antomani103@gmail.com>]

On 9/6/24 10:11 PM, Akhil P Oommen wrote:
> On Thu, Sep 05, 2024 at 04:51:25PM +0200, Antonino Maniscalco wrote:
>> Add trace points corresponding to preemption being triggered and being
>> completed for latency measurement purposes.
>>
>> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
>> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
>> ---
>>   drivers/gpu/drm/msm/adreno/a6xx_preempt.c |  7 +++++++
>>   drivers/gpu/drm/msm/msm_gpu_trace.h       | 28 ++++++++++++++++++++++++++++
>>   2 files changed, 35 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
>> index ec44f44d925f..ca9d36c107f2 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
>> @@ -7,6 +7,7 @@
>>   #include "a6xx_gpu.h"
>>   #include "a6xx_gmu.xml.h"
>>   #include "msm_mmu.h"
>> +#include "msm_gpu_trace.h"
>>   
>>   /*
>>    * Try to transition the preemption state from old to new. Return
>> @@ -143,6 +144,8 @@ void a6xx_preempt_irq(struct msm_gpu *gpu)
>>   
>>   	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
>>   
>> +	trace_msm_gpu_preemption_irq(a6xx_gpu->cur_ring->id);
>> +
>>   	/*
>>   	 * Retrigger preemption to avoid a deadlock that might occur when preemption
>>   	 * is skipped due to it being already in flight when requested.
>> @@ -264,6 +267,10 @@ void a6xx_preempt_trigger(struct msm_gpu *gpu)
>>   	 */
>>   	ring->skip_inline_wptr = false;
>>   
>> +	trace_msm_gpu_preemption_trigger(
>> +		a6xx_gpu->cur_ring ? a6xx_gpu->cur_ring->id : -1,
> 
> Can't we avoid this check?
>
Sorry yeah you had requested this change but I had forgotten to do it.

> -Akhil.
> 
>> +		ring ? ring->id : -1);
>> +
>>   	spin_unlock_irqrestore(&ring->preempt_lock, flags);
>>   
>>   	gpu_write64(gpu,
>> diff --git a/drivers/gpu/drm/msm/msm_gpu_trace.h b/drivers/gpu/drm/msm/msm_gpu_trace.h
>> index ac40d857bc45..7f863282db0d 100644
>> --- a/drivers/gpu/drm/msm/msm_gpu_trace.h
>> +++ b/drivers/gpu/drm/msm/msm_gpu_trace.h
>> @@ -177,6 +177,34 @@ TRACE_EVENT(msm_gpu_resume,
>>   		TP_printk("%u", __entry->dummy)
>>   );
>>   
>> +TRACE_EVENT(msm_gpu_preemption_trigger,
>> +		TP_PROTO(int ring_id_from, int ring_id_to),
>> +		TP_ARGS(ring_id_from, ring_id_to),
>> +		TP_STRUCT__entry(
>> +			__field(int, ring_id_from)
>> +			__field(int, ring_id_to)
>> +			),
>> +		TP_fast_assign(
>> +			__entry->ring_id_from = ring_id_from;
>> +			__entry->ring_id_to = ring_id_to;
>> +			),
>> +		TP_printk("preempting %u -> %u",
>> +			  __entry->ring_id_from,
>> +			  __entry->ring_id_to)
>> +);
>> +
>> +TRACE_EVENT(msm_gpu_preemption_irq,
>> +		TP_PROTO(u32 ring_id),
>> +		TP_ARGS(ring_id),
>> +		TP_STRUCT__entry(
>> +			__field(u32, ring_id)
>> +			),
>> +		TP_fast_assign(
>> +			__entry->ring_id = ring_id;
>> +			),
>> +		TP_printk("preempted to %u", __entry->ring_id)
>> +);
>> +
>>   #endif
>>   
>>   #undef TRACE_INCLUDE_PATH
>>
>> -- 
>> 2.46.0
>>

Best regards,
-- 
Antonino Maniscalco <antomani103@gmail.com>