Performance-Boosting DCC Support Being Worked On For RadeonSI VI GPUs

[phoronix]

Phoronix: Performance-Boosting DCC Support Being Worked On For RadeonSI VI GPUs

Bas Nieuwenhuizen has been working on enabling Delta Color Compression (DCC) support for newer AMD Volcanic Islands (VI) GPUs within the RadeonSI Gallium3D driver...

http://www.phoronix.com/scan.php?page=news_item&px=RadeonSI-DCC-VI-GPUs

[Kemosabe]

Bandwith is the biggest issue with radeon/radeonsi? I experienced quite bad performance on AMD APUs compared to dedicated GPUs driven by mesa drivers. Or what exactly makes catalyst perform better (if it performs at all ).

[blubbaer]

Bandwidth is a big problem for todays GPUs. Back in the days of Geforce FX, it was recommended to use LUTs in form of textures. Few generations later (about Geforce 8) bandwidth was a big problem and the recommendation was to use the ALU instead of textures. This was also the time where everybody talked big about bandwidth-saving techniques like HyperZ, texture compression and framebuffer compression.
You can also read the excellent article series about GPUs from Fabian Giesen to get more knowledge why bandwidth is important for GPUs.

[swoorup]

I wonder why compression outweighs the bandwidth?

[profoundWHALE]

I wonder why compression outweighs the bandwidth?

Because less things have to travel through the same sized pipe. Hence, compression.

[smitty3268]

I wonder why compression outweighs the bandwidth?

The compression is done in the hardware for free (only with GCN 1.2 hardware, obviously), so there's no reason not to use it.

Well, except if you read the patches you see that certain features aren't supported when compression is used, so they have to be smart about that.

[swoorup]

That makes sense, when compression is hardware accelerated, they are not wasting much cycles at all.?

[dungeon]

That makes sense, when compression is hardware accelerated, they are not wasting much cycles at all.?

DCC (delta color compression) is hardware feature, means you shoudn't think of it... it is not sort of let say s3tc compression which userspace driver can implement and then application can use / control to save some bandwidth... this DCC works all along, neither app knows about it... even neither OS knows it is there

[Kemosabe]

((...) You can also read the excellent article series about GPUs from Fabian Giesen to get more knowledge why bandwidth is important for GPUs.

Sweet. Thank you!