[PATCH 0/5] *** Dedicated vmid per process ***

[Christian König]

Am 21.04.2017 um 18:27 schrieb Deucher, Alexander:
>> -----Original Message-----
>> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
>> Of Chunming Zhou
>> Sent: Friday, April 21, 2017 6:06 AM
>> To: amd-gfx at lists.freedesktop.org
>> Cc: Zhou, David(ChunMing)
>> Subject: [PATCH 0/5] *** Dedicated vmid per process ***
>>
>> The current kernel implementation, which grabs the idle VMID from pool
>> when emitting the job may:
>>
>>      The back-to-back submission from one process could use different VMID.
>>      The submission to different queues from single process could use different
>> VMID
>>
>> It works well in most case but cannot work for the SQ thread trace capture.
>>
>> The VMID for the submission that set the {SQTT}_BASE, which refers to the
>> address of the trace buffer, is stored in shader engine.
>>
>> If the profiling application have to use different VMIDs to submit IBs in its life
>> cycle:
>>
>>      Some trace is not captured since it actually uses different VMID to submit
>> jobs.
>>      Some part of captured trace may come from different application since
>> they are accidentally uses the owner’s VMID to submit jobs.
> Please add a patch at the end to bump the module version so we can track when the flag is available.

Additional to that we might want to reconsider the interface once more.

When we see a context with that flag we assign a permanent ID to the VM 
and never free until the process exits. That is quite ugly.

I would either suggest to add an atomic and alloc/free the VMID when the 
first/last context needing it for a trace in a process is created/freed.

Or completely drop the per context flag and add a new IOCTL to enable it 
for the whole process.

I prefer option #2, but that is clearly more work.

Regards,
Christian.

>
> Alex
>
>>
>> ChunmingrZhour(5):
>>    drm/amdgpu: handle flags when context alloc
>>    drm/amdgpu: add dedicated vmid field in vm struct
>>    drm/amdgpu: add context flagn for dedicated vmid reqest
>>    drm/amdgpu: implement grab dedicated vmid
>>    drm/amdgpu: add limitation for dedicated vm number
>>
>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h        |   1 +
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c    |  14 ++-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |   1 +
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c     | 137
>> ++++++++++++++++++++++++++++-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h     |   6 ++
>>   include/uapi/drm/amdgpu_drm.h              |   3 +
>>   6 files changed, 158 insertions(+), 4 deletions(-)
>>
>> --
>> 1.9.1
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