[Mesa-dev] [PATCH 00/13] RadeonSI: Reduce user SGPR usage

[Marek Olšák]

So what is wrong with patches 9-13?

We can do cleanups after those.

Marek

On Thu, Feb 22, 2018 at 5:17 PM, Marek Olšák <maraeo at gmail.com> wrote:
> I don't think that adding "uint32_t userdata_XX[16];" would simplify anything.
>
> The bottom line is, patches 9-13 are prerequisites for VBO descriptors
> in user SGPRs, so they block that optimization as long as they sit on
> the mailing list.
>
> Marek
>
> On Tue, Feb 20, 2018 at 8:51 PM, Marek Olšák <maraeo at gmail.com> wrote:
>> The user SGPRs for blits are kinda a separate thing where the standard
>> emit paths are disabled. 64-bit pointers are a short-term issue and
>> will be removed in 2 years (or 1.5 years or when we want to kill off
>> old LLVM support). VBO descriptors in user SGPRs will require 32-bit
>> pointers. Next-gen will also require 32-bit pointers. The number of
>> codepaths will be reduced to merged/non-merged and mono/non-mono
>> again. For gfx9 and later, the only codepaths will be mono/non-mono.
>>
>> There will just be a transitory period when both 32-bit and 64-bit
>> pointers will be supported, and both the old and new way of setting up
>> VBO descriptors will be supported. However, next-gen will only support
>> one way - the newer way.
>>
>> Overall, I don't see an increase in complexity other than the transitory period.
>>
>> Marek
>>
>> On Tue, Feb 20, 2018 at 5:46 PM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
>>> With a small comment on patch 6, patches 1-8:
>>>
>>> Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
>>>
>>> for now.
>>>
>>> However, I'm unhappy about how complex this is all getting. 32- vs. 64-bit,
>>> merged vs. non-merged, monolithic vs. non-monolithic, and then special user
>>> SGPR uses like for blits and soon VBO descriptors, it feels like it's
>>> becoming too much.
>>>
>>> The problem is I don't have a good answer to it all :)
>>>
>>> Perhaps some of it could be helped by having an explicit userdata staging
>>> area, i.e.
>>>
>>>   uint32_t userdata_XX[16]; // or 32
>>>   uint32_t userdata_XX_dirty;
>>>
>>> Then si_upload_descriptors would write its pointers into userdata_XX in the
>>> right location and set the appropriate dirty bit(s), and a separate
>>> emit_userdata function would use the contiguous bit scan to actually emit
>>> all the userdata together -- this would include VS state bits, tess state
>>> info, and blit shader SGPRs.
>>>
>>> I do think this would be cleaner especially than the current
>>> si_emit_shader_pointer_* code, and it would coalesce more SH reg writes as a
>>> side bonus. What do you think?
>>>
>>> The other half of it is how the LLVM functions are created.
>>>
>>> Thanks,
>>> Nicolai
>>>
>>>
>>> On 17.02.2018 20:43, Marek Olšák wrote:
>>>>
>>>> Hi,
>>>>
>>>> This series has the following effect on user SGPRs:
>>>>
>>>> 64-bit pointers:
>>>>      TCS:    14 -> 12
>>>>      Merged VS-TCS: 24 -> 20
>>>>      Merged VS-GS:  18 -> 16
>>>>      Merged TES-GS: 18 -> 14
>>>>
>>>> 32-bit pointers:
>>>>      TCS:    10 -> 8
>>>>      Merged VS-TCS: 16 -> 12
>>>>      Merged VS-GS:  11 -> 9
>>>>      Merged TES-GS: 11 -> 6
>>>>
>>>> I tested both monolithic and non-monolithic shaders, and both 64-bit
>>>> and 32-bit pointers. (4 combinations)
>>>>
>>>> This series is a prerequisite for VBO descriptors in user SGPRs.
>>>>
>>>> Note that merged LS-HS and ES-GS don't even use s[6:7] input SGPRs
>>>> yet. Those only provide 40 bits of scalar data (not 64 bits like
>>>> s[0:1]).
>>>>
>>>> Please review.
>>>>
>>>> Thanks,
>>>> Marek
>>>> _______________________________________________
>>>> mesa-dev mailing list
>>>> mesa-dev at lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>>>>
>>>
>>>
>>> --
>>> Lerne, wie die Welt wirklich ist,
>>> Aber vergiss niemals, wie sie sein sollte.