Hi,
I am the main developer of the TimeGraph GPU command scheduler, which was presented at XDC 2011 in Chicago a few days ago. Please let me propose this approach to scheduling GPU-accelerated processes with DRM.
This GPU scheduler will help to prioritize and isolate multiple GPU-accelerated processes executing concurrently for protecting important GPU workload in multi-tasking environments. It is designed and implemented at the DRM level as a "drm_sched" component. Each architecture-dependent driver (nouveau, radeon, i915, etc.) is also required to call the scheduling functions provided by this drm_sched component accordingly. Nothing needs to be changed in user-space runtimes. The priorities and resource limits can be specified through "/proc/driver/drm_sched/#PID/{sched_policy,resv_policy,priority,runtime,peri od}" and/or "/etc/drm_sched.spec". Other user interfaces could also be possible. The impact of prioritization and isolation on protecting important GPU-accelerated processes from competing GPU workload is quite significant (e.g., 3-D games can run at a 10x~ faster rate, using our GPU scheduler, when heavy workload is competing the GPU). Performance interference among GPU-accelerated processes can also be well-controlled. We can activate this GPU scheduler only when multiple processes use the GPU. Hence *nothing* would be harmful for a standalone execution. I felt that the audience at XDC 2011 was pretty supportive for this idea.
TimeGraph is developed in a collaborative project with Carnegie Mellon University, University of California Santa Cruz, and University of Tokyo. The project website is: http://rtml.ece.cmu.edu/projects/timegraph/
The documentation about how it works is: http://rtml.ece.cmu.edu/projects/timegraph/raw-attachment/wiki/documentation /drm_sched_rtgpu.pdf More information is available at: http://rtml.ece.cmu.edu/projects/timegraph/wiki/documentation
The instruction to install our Nouveau-based prototype driver is: http://rtml.ece.cmu.edu/projects/timegraph/wiki/install For convenience of development, the GPU scheduler is provided as an independent kernel module (https://gitorious.org/rtgpu/timegraph), but it can also be part of DRM. You will also need the Nouveau-tree Linux kernel patched for drm_sched (https://gitorious.org/rtgpu/linux-rtgpu). Please see the instruction above. There are not so many changes applied to the current kernel code, as you can quickly reference at: http://rtml.ece.cmu.edu/projects/timegraph/attachment/wiki/install/linux-rtg pu.patch
I would appreciate any comments and feedback from you.
Best Regards, - Shinpei Kato