On 08/21/2018 06:10 AM, Axel Davy wrote: > On 23/06/2018 07:03, Ian Romanick wrote: >> I initially started implementing support for NV_shader_atomic_float. I >> had misunderstood the hardware specs, and Intel hardware cannot actually >> do that extension. It does have some floating-point atomic support, so >> I decided to create an extension based on what the hardware actually can >> do. I discussed this with some guys at AMD and NVIDIA, and it seems >> nobody else can do these things. > > Hi, > > > Older AMD SI chips had the functionality, as can be seen here: > > https://developer.amd.com/wordpress/media/2012/12/AMD_Southern_Islands_Instruction_Set_Architecture.pdf > > > > It features BUFFER_ATOMIC_FMIN, BUFFER_ATOMIC_FCMPSWAP and > BUFFER_ATOMIC_FMAX. > > The feature seems to have been dropped with later iterations of GCN.
Yeah, that's basically what Marek told me on IRC. > Reading the spec of intel broadwell, there are some sections mentioning > atomic float add, > > https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-bdw-vol07-3d_media_gpgpu_3.pdf > > > > But there is no mention of it for Skylake. Maybe it was supported, but > dropped ? That bit of documentation is the reason I started working on the NV extension. As far as I can tell, the feature was planned, but it was never implemented. I spent a whole day trying to figure out why I was hanging the GPU before I realized it was because the hardware did not support that feature. :( > Yours, > > Axel Davy _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
