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

Shashank Sharma shashank.sharma at amd.com
Wed Aug 19 12:37:17 UTC 2020


On 19/08/20 6:03 pm, Christian König wrote:
> Am 19.08.20 um 14:19 schrieb Shashank Sharma:
>> On 19/08/20 5:38 pm, Christian König wrote:
>>> Am 19.08.20 um 13:52 schrieb 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 ?
>>> That is vm->task_info.pid, since this is the PID which is using the VM
>>> for command submission.
>> got it.
>>>> 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 ?
>>> Only in trace_amdgpu_vm_grab_id(), in all other cases it's probably not
>>> assigned yet.
>> Ok, let me check how can we get vmid from this context we are sending the event from. Or maybe I we should  keep V5 with pid only, and later send a separate patch to add vmid ?
> I'm not sure how you want to get a VMID in the first place. We 
> dynamically assign VMIDs during command submission.
>
> See the amdgpu_vm_grab_id trace point.

Actually I was adding vmid to address this last comment on V4: 
> and probably the VM context ID we use here to identify the updated VM.

I assumed you meant the vmid by this, is that not so ?


Regards

Shashank

>
> Christian.
>
>> - Shashank
>>
>>> Christian.
>>>
>>>> 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) {
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