[PATCH v4] drm/amdgpu: add new trace event for page table update v3

[Shashank Sharma]

On 13/08/20 1:28 pm, Christian König wrote:
> Am 13.08.20 um 05:04 schrieb Shashank Sharma:
>> This patch adds a new trace event to track the PTE update
>> events. This specific event will provide information like:
>> - start and end of virtual memory mapping
>> - HW engine flags for the map
>> - physical address for mapping
>>
>> This will be particularly useful for memory profiling tools
>> (like RMV) which are monitoring the page table update events.
>>
>> V2: Added physical address lookup logic in trace point
>> V3: switch to use __dynamic_array
>>      added nptes int the TPprint arguments list
>>      added page size in the arg list
>> V4: Addressed Christian's review comments
>>      add start/end instead of seg
>>      use incr instead of page_sz to be accurate
>>
>> Cc: Christian König <christian.koenig at amd.com>
>> Cc: Alex Deucher <alexander.deucher at amd.com>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h | 37 +++++++++++++++++++++++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c    |  9 ++++--
>>   2 files changed, 44 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h
>> index 63e734a125fb..df12cf8466c2 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_trace.h
>> @@ -321,6 +321,43 @@ DEFINE_EVENT(amdgpu_vm_mapping, amdgpu_vm_bo_cs,
>>   	    TP_ARGS(mapping)
>>   );
>>   
>> +TRACE_EVENT(amdgpu_vm_update_ptes,
>> +	    TP_PROTO(struct amdgpu_vm_update_params *p,
>> +		     uint64_t start, uint64_t end,
>> +		     unsigned int nptes, uint64_t dst,
>> +		     uint64_t incr, uint64_t flags),
>> +	TP_ARGS(p, start, end, nptes, dst, incr, flags),
>> +	TP_STRUCT__entry(
>> +			 __field(u64, start)
>> +			 __field(u64, end)
>> +			 __field(u64, flags)
>> +			 __field(unsigned int, nptes)
>> +			 __field(u64, incr)
>> +			 __dynamic_array(u64, dst, nptes)
> As discussed with the trace subsystem maintainer we need to add the pid 
> and probably the VM context ID we use here to identify the updated VM.
>
> Christian.

I printed both vm->task_info.pid Vs current->pid for testing, and I can see different values coming out of .

gnome-shell-2114  [011]    41.812894: amdgpu_vm_update_ptes: start:0x0800102e80 end:0x0800102e82, flags:0x80, incr:4096, pid=2128 vmid=0 cpid=2114

pid is vm->task_info.pid=2128 whereas cpid=2114 is current.pid.

Which is the one we want to send with the event ?

Trace event by default seems to be adding the process name and id at the header of the event (gnome-shell-2114), which is same as current.pid


Also, is it ok to extract vmid from job->vmid ?


Regards

Shashank

>
>> +	),
>> +
>> +	TP_fast_assign(
>> +			unsigned int i;
>> +
>> +			__entry->start = start;
>> +			__entry->end = end;
>> +			__entry->flags = flags;
>> +			__entry->incr = incr;
>> +			__entry->nptes = nptes;
>> +			for (i = 0; i < nptes; ++i) {
>> +				u64 addr = p->pages_addr ? amdgpu_vm_map_gart(
>> +					p->pages_addr, dst) : dst;
>> +
>> +				((u64 *)__get_dynamic_array(dst))[i] = addr;
>> +				dst += incr;
>> +			}
>> +	),
>> +	TP_printk("start:0x%010llx end:0x%010llx, flags:0x%llx, incr:%llu,"
>> +		  " dst:\n%s", __entry->start, __entry->end, __entry->flags,
>> +		  __entry->incr, __print_array(
>> +		  __get_dynamic_array(dst), __entry->nptes, 8))
>> +);
>> +
>>   TRACE_EVENT(amdgpu_vm_set_ptes,
>>   	    TP_PROTO(uint64_t pe, uint64_t addr, unsigned count,
>>   		     uint32_t incr, uint64_t flags, bool direct),
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index 71e005cf2952..b5dbb5e8bc61 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -1513,17 +1513,22 @@ static int amdgpu_vm_update_ptes(struct amdgpu_vm_update_params *params,
>>   		do {
>>   			uint64_t upd_end = min(entry_end, frag_end);
>>   			unsigned nptes = (upd_end - frag_start) >> shift;
>> +			uint64_t upd_flags = flags | AMDGPU_PTE_FRAG(frag);
>>   
>>   			/* This can happen when we set higher level PDs to
>>   			 * silent to stop fault floods.
>>   			 */
>>   			nptes = max(nptes, 1u);
>> +
>> +			trace_amdgpu_vm_update_ptes(params, frag_start, upd_end,
>> +						    nptes, dst, incr,
>> +						    upd_flags);
>>   			amdgpu_vm_update_flags(params, pt, cursor.level,
>>   					       pe_start, dst, nptes, incr,
>> -					       flags | AMDGPU_PTE_FRAG(frag));
>> +					       upd_flags);
>>   
>>   			pe_start += nptes * 8;
>> -			dst += (uint64_t)nptes * AMDGPU_GPU_PAGE_SIZE << shift;
>> +			dst += nptes * incr;
>>   
>>   			frag_start = upd_end;
>>   			if (frag_start >= frag_end) {