[PATCH v3] drm/amdgpu: Add debugfs entry for printing VM info

[Patel, Mihir]

[AMD Official Use Only - Internal Distribution Only]



-----Original Message-----
From: Koenig, Christian <Christian.Koenig at amd.com> 
Sent: Monday, October 12, 2020 4:24 PM
To: Patel, Mihir <Mihir.Patel at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Chauhan, Madhav <Madhav.Chauhan at amd.com>; Deucher, Alexander <Alexander.Deucher at amd.com>; Kamliya, Prakash <Prakash.Kamliya at amd.com>; Surampalli, Kishore <Kishore.Surampalli at amd.com>
Subject: Re: [PATCH v3] drm/amdgpu: Add debugfs entry for printing VM info

Am 12.10.20 um 12:50 schrieb Christian König:
> Am 12.10.20 um 12:00 schrieb Patel, Mihir:
>> [AMD Official Use Only - Internal Distribution Only]
>>
>>
>>
>> -----Original Message-----
>> From: Koenig, Christian <Christian.Koenig at amd.com>
>> Sent: Monday, October 12, 2020 3:14 PM
>> To: Patel, Mihir <Mihir.Patel at amd.com>; amd-gfx at lists.freedesktop.org
>> Cc: Chauhan, Madhav <Madhav.Chauhan at amd.com>; Deucher, Alexander 
>> <Alexander.Deucher at amd.com>; Surampalli, Kishore 
>> <Kishore.Surampalli at amd.com>; Kamliya, Prakash 
>> <Prakash.Kamliya at amd.com>
>> Subject: Re: [PATCH v3] drm/amdgpu: Add debugfs entry for printing VM 
>> info
>>
>> [SNIP]
>>> Hi Christian,
>>> One question regarding getting total allocations by app and also 
>>> swapped size for the app.
>>> Shouldn’t we print mapped entries as well to get total allocation by 
>>> the process ?
>>> Also which list would represent swapped memory?
>> None, we don't really have that information anywhere since we don't 
>> really have a swapped state.
>>
>> See when the application allocates a BO in VRAM the kernel driver is 
>> free to swap it out to GTT and still do command submission. Only when 
>> it is further swapped out to the CPU domain it is not accessible any 
>> more.
>>
>> So what you can do is to look at the BOs in the CPU domain, but this 
>> only gives you a certain hint on what's going on.
>>
>> Regards,
>> Christian.
>>
>> Thanks Christian for clarifying about swapped memory. How about total 
>> allocated size? Can't we print mapped BOs since amdgpu_gem_info is 
>> FILE/gem handle based?
>
> That's what you are already printing. E.g. if you sum up all the BOs 
> in all the different states then you have the total amount of 
> allocated memory for this process.
>
> Even if some of that memory isn't mapped into the VM.

Thinking a bit more about it, when you also look at 
bo->preferred_domains and compare that with the current domain you can
also figure out if a BO is swapped out or not.

Christian.

Thanks again Christian. We are mostly interested in GTT to CPU swap. We would like to add this info as well in future patch.
Addressed other comments in Patch V4.
>
> Christian.
>
>> Regards,
>> Mihir
>>> Thanks,
>>> Mihir
>
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