[Mesa-dev] [PATCH 2/2] RFC: radeon/compute: Limit allocations for VRAM-based chips to 3/4 VRAM

[Aaron Watry]

On Wed, Jun 7, 2017 at 9:15 PM, Michel Dänzer <michel at daenzer.net> wrote:
> On 08/06/17 03:42 AM, Marek Olšák wrote:
>> On Wed, Jun 7, 2017 at 4:10 PM, Aaron Watry <awatry at gmail.com> wrote:
>>> On Mon, Jun 5, 2017 at 3:07 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>>
>>>> Can you make the change in radeon_drm_winsys.c instead?
>>>
>>> Something like the following?
>>>
>>> diff --git a/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c
>>> b/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c
>>> index a485615ae4..44948f49ef 100644
>>> --- a/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c
>>> +++ b/src/gallium/winsys/radeon/drm/radeon_drm_winsys.c
>>> @@ -365,6 +365,8 @@ static bool do_winsys_init(struct radeon_drm_winsys *ws)
>>>      /* Radeon allocates all buffers as contigous, which makes large allocations
>>>       * unlikely to succeed. */
>>>      ws->info.max_alloc_size = MAX2(ws->info.vram_size,
>>> ws->info.gart_size) * 0.7;
>>> +    if (ws->info.has_dedicated_vram)
>>> +        ws->info.max_alloc_size = MIN2(ws->info.vram_size * 0.7,
>>> ws->info.max_alloc_size);
>>>      if (ws->info.drm_minor < 40)
>>>          ws->info.max_alloc_size = MIN2(ws->info.max_alloc_size, 256*1024*1024);
>>
>> Yes, feel free to push that.
>
> That also affects PIPE_CAP_MAX_TEXTURE_BUFFER_SIZE, is that intended?

Not necessarily.

Part of the reason that I had originally put this in
r600_pipe_common.c under the compute params was that I didn't feel
comfortable changing this for all workload types. There's evidence
that implies that the closed-source AMD CL runtime limits global
allocations to either 256MB or 1/4 VRAM (on a 1GB card), so 70% of the
max of GART/VRAM seems a bit high for us to report. I'll probably
check around a bit and see what the prevailing limits seem to be and
if lowering the absolute max might make sense here (for compute loads
only), as a failure to allocate the requested amount of memory seems
to result in system hangs shortly thereafter, and I'd like to get the
frequency of those occurrences down a bit.

--Aaron



> --
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer