On Tue, Jul 07, 2015 at 08:13:28PM -0400, Ilia Mirkin wrote: > On Tue, Jul 7, 2015 at 8:11 PM, C Bergström <cbergst...@pathscale.com> wrote: > > On Wed, Jul 8, 2015 at 7:08 AM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > >> On Tue, Jul 7, 2015 at 8:07 PM, C Bergström <cbergst...@pathscale.com> > >> wrote: > >>> On Wed, Jul 8, 2015 at 6:58 AM, Ben Skeggs <skeg...@gmail.com> wrote: > >>>> On 8 July 2015 at 09:53, C Bergström <cbergst...@pathscale.com> wrote: > >>>>> regarding > >>>>> -------- > >>>>> Fixed address allocations weren't going to be part of that, but I see > >>>>> that it makes sense for a variety of use cases. One question I have > >>>>> here is how this is intended to work where the RM needs to make some > >>>>> of these allocations itself (for graphics context mapping, etc), how > >>>>> should potential conflicts with user mappings be handled? > >>>>> -------- > >>>>> As an initial implemetation you can probably assume that the GPU > >>>>> offloading is in "exclusive" mode. Basically that the CUDA or OpenACC > >>>>> code has full ownership of the card. The Tesla cards don't even have a > >>>>> video out on them. To complicate this even more - some offloading code > >>>>> has very long running kernels and even worse - may critically depend > >>>>> on using the full available GPU ram. (Large matrix sizes and soon big > >>>>> Fortran arrays or complex data types) > >>>> This doesn't change that, to setup the graphics engine, the driver > >>>> needs to map various system-use data structures into the channel's > >>>> address space *somewhere* :) > >>> > >>> I'm not sure I follow exactly what you mean, but I think the answer is > >>> - don't setup the graphics engine if you're in "compute" mode. Doing > >>> that, iiuc, will at least provide a start to support for compute. > >>> Anyone who argues that graphics+compute is critical to have working at > >>> the same time is probably a 1%. > >> > >> On NVIDIA GPUs, compute _is_ part of the graphics engine... aka PGRAPH. > > > > You can afaik setup PGRAPH without mapping memory for graphics. You > > just init the engine and get out of the way. > > But... you need to map memory to set up the engine. Not a lot, but > it's gotta go *somewhere*.
There's some minimal state that needs to be mapped into GPU address space. One thing that comes to mind are pushbuffers, which are needed to submit stuff to any engine. _______________________________________________ Nouveau mailing list Nouveau@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/nouveau
