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

[Chauhan, Madhav]

[AMD Public Use]

-----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 Christian for quick review/help and details. Summarizing your inputs  and some queries:
1. Adding BO from all the lists will give the total amount of memory allocated by this PID
2.  We can also print bo->preferred domain to check what user asked for and where it is currently. 
But we can have a situation where user asked for VRAM but allowed domain added GTT and we eventually
Allocated BO in GTT. So do we update bo->preferred_domain in that scenario??
3. What will be the scenario in which we add BO to the Reloacted/Moved/Idle?? How it is different from Evicted??

Regards,
Madhav

>
> Christian.
>
>> Regards,
>> Mihir
>>> Thanks,
>>> Mihir
>
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