Re: [PATCH 2/2] drm/amdgpu: add shared fdinfo stats

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 09/01/2024 07:56, Christian König wrote:
> Am 07.12.23 um 19:02 schrieb Alex Deucher:
>> Add shared stats.  Useful for seeing shared memory.
>>
>> v2: take dma-buf into account as well
>>
>> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>> Cc: Rob Clark <robdclark@gmail.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c |  4 ++++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 11 +++++++++++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.h |  6 ++++++
>>   3 files changed, 21 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c
>> index 5706b282a0c7..c7df7fa3459f 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c
>> @@ -97,6 +97,10 @@ void amdgpu_show_fdinfo(struct drm_printer *p, 
>> struct drm_file *file)
>>              stats.requested_visible_vram/1024UL);
>>       drm_printf(p, "amd-requested-gtt:\t%llu KiB\n",
>>              stats.requested_gtt/1024UL);
>> +    drm_printf(p, "drm-shared-vram:\t%llu KiB\n", 
>> stats.vram_shared/1024UL);
>> +    drm_printf(p, "drm-shared-gtt:\t%llu KiB\n", 
>> stats.gtt_shared/1024UL);
>> +    drm_printf(p, "drm-shared-cpu:\t%llu KiB\n", 
>> stats.cpu_shared/1024UL);
>> +
>>       for (hw_ip = 0; hw_ip < AMDGPU_HW_IP_NUM; ++hw_ip) {
>>           if (!usage[hw_ip])
>>               continue;
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> index d79b4ca1ecfc..1b37d95475b8 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> @@ -1287,25 +1287,36 @@ void amdgpu_bo_get_memory(struct amdgpu_bo *bo,
>>                 struct amdgpu_mem_stats *stats)
>>   {
>>       uint64_t size = amdgpu_bo_size(bo);
>> +    struct drm_gem_object *obj;
>>       unsigned int domain;
>> +    bool shared;
>>       /* Abort if the BO doesn't currently have a backing store */
>>       if (!bo->tbo.resource)
>>           return;
>> +    obj = &bo->tbo.base;
>> +    shared = (obj->handle_count > 1) || obj->dma_buf;
> 
> I still think that looking at handle_count is the completely wrong 
> approach, we should really only look at obj->dma_buf.

Yeah it is all a bit tricky with the handle table walk. I don't think it 
is even possible to claim it is shared with obj->dma_buf could be the 
same process creating say via udmabuf and importing into drm. It is a 
wild scenario yes, but it could be private memory in that case. Not sure 
where it would leave us if we said this is just a limitation of a BO 
based tracking.

Would adding a new category "imported" help?

Hmm or we simply change drm-usage-stats.rst:

"""
- drm-shared-<region>: <uint> [KiB|MiB]

The total size of buffers that are shared with another file (ie. have 
more than than a single handle).
"""

Changing ie into eg coule be get our of jail free card to allow the 
"(obj->handle_count > 1) || obj->dma_buf;" condition?

Because of the shared with another _file_ wording would cover my wild 
udmabuf self-import case. Unless there are more such creative private 
import options.

Regards,

Tvrtko

> 
> Regards,
> Christian.
> 
>> +
>>       domain = amdgpu_mem_type_to_domain(bo->tbo.resource->mem_type);
>>       switch (domain) {
>>       case AMDGPU_GEM_DOMAIN_VRAM:
>>           stats->vram += size;
>>           if (amdgpu_bo_in_cpu_visible_vram(bo))
>>               stats->visible_vram += size;
>> +        if (shared)
>> +            stats->vram_shared += size;
>>           break;
>>       case AMDGPU_GEM_DOMAIN_GTT:
>>           stats->gtt += size;
>> +        if (shared)
>> +            stats->gtt_shared += size;
>>           break;
>>       case AMDGPU_GEM_DOMAIN_CPU:
>>       default:
>>           stats->cpu += size;
>> +        if (shared)
>> +            stats->cpu_shared += size;
>>           break;
>>       }
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>> index d28e21baef16..0503af75dc26 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>> @@ -138,12 +138,18 @@ struct amdgpu_bo_vm {
>>   struct amdgpu_mem_stats {
>>       /* current VRAM usage, includes visible VRAM */
>>       uint64_t vram;
>> +    /* current shared VRAM usage, includes visible VRAM */
>> +    uint64_t vram_shared;
>>       /* current visible VRAM usage */
>>       uint64_t visible_vram;
>>       /* current GTT usage */
>>       uint64_t gtt;
>> +    /* current shared GTT usage */
>> +    uint64_t gtt_shared;
>>       /* current system memory usage */
>>       uint64_t cpu;
>> +    /* current shared system memory usage */
>> +    uint64_t cpu_shared;
>>       /* sum of evicted buffers, includes visible VRAM */
>>       uint64_t evicted_vram;
>>       /* sum of evicted buffers due to CPU access */
>