ATI Radeon CrossFire On Linux
Phoronix: ATI Radeon CrossFire On Linux
Back in June we had exclusively shared that CrossFire would be coming to Linux as part of their Radeon HD 4800 series strategy. CrossFire (or CrossFire X as it's now known) allows the graphics rendering workload to be split between multiple Radeon GPUs to deliver faster performance. Meanwhile, NVIDIA's multi-GPU technology known as SLI (Scalable Link Interface) has been supported on Linux since 2005. While AMD is still working to address some issues with their ATI Linux driver, they have been working hard on new features like CrossFire. How does this feature work though on Linux and does it deliver similar performance gains to their Windows driver? Today we have a full rundown on ATI CrossFire for Linux along with benchmarks from the ATI Radeon HD 4850 and Radeon HD 4870.
This is awesome, I've been waiting for this for a while now(this and gpu monitoring/overclocking). Now we just need rv770 register documentation and a new Stream Processing SDK to be released for full rv770 support on linux
AMD has dumped CTM and is now focusing it's efforts on openCL.
Originally Posted by tcoppi
Someone please tell me I was imagining when I saw the 4850 beat the 4870 in one of the tests: how is that even possible?
It's the second test on page 8 of the review.
Originally Posted by dashcloud
By like 2 frames. The difference is so small in relation to overall performance that it really should not matter. And if you notice, the test in question is without post-processing effects; we saw similar behavior when the HD4850/70 were tested.
Those are the two cards they are referring to, it's strange that the 50 can ever beat the 70 when it's the same chipset but the 70 is running faster and with more mem (I think) and such. You'd think such results would never happen unless there was a testing error or some artificial or software barrier, like with the drivers. For instance maybe the driver does something a little more slowly for basic stuff when dealing with more, say, GPU RAM, while that small mismanagement performance issue won't normally be noticed when pushing the cards a little harder.
Originally Posted by Melcar
Still strange to see it regardless, but perhaps as their driver gets better, that performance bug will go away.
I know that only the new 4850 and 4870 are supported with Crossfire now, but does anyone know of ATI's plans for the future. Will they support older cards and specifically Hybrid Crossfire?
I know that the Catalyst 8.8 do not officially support x.org 7.4. It's normal because x.org 7.4 is not now a final version. But, is it possible to use this driver on x.org 7.4?
Cool feature, glad it finally came, the name-based decision for engaging multi-GPUs is very silly though. I want multiple GPUs to be used whenever one gets stressed, or to split the work all of the time to keep the cards balanced, so it's sad to see that it's such a top-level implementation. I guess that comes with the difficulties of trying to get two normally very separate cards functioning as one, but it would be nice to see all resources including the frame buffers being effectively pooled together to act as one on a very low level. Perhaps in the future.
Ok, I was able to set up Crossfire, but I can only set the fan speed on the first card, how can I set the fanspeed on the second card and is there a way to have the changed fan speed set permanently without flashing the BIOS? My Crossfired 4870s get way way way too hot without fan speed set higher.