On Wed, Jul 23, 2014 at 04:57:48PM -0700, Jesse Barnes wrote: > On Sun, 13 Jul 2014 12:40:32 -0400 > j.glisse at gmail.com (Jerome Glisse) wrote: > > > On Sun, Jul 13, 2014 at 11:42:58AM +0200, Daniel Vetter wrote: > > > On Sat, Jul 12, 2014 at 6:49 PM, Jerome Glisse <j.glisse at gmail.com> > > > wrote: > > > >> Hm, so the hsa part is a completely new driver/subsystem, not just an > > > >> additional ioctl tacked onto radoen? The history of drm is littered > > > >> with > > > >> "generic" ioctls that turned out to be useful for exactly one driver. > > > >> Which is why _all_ the command submission is now done with > > > >> driver-private > > > >> ioctls. > > > >> > > > >> I'd be quite a bit surprised if that suddenly works differently, so > > > >> before > > > >> we bless a generic hsa interface I really want to see some > > > >> implementation > > > >> from a different vendor (i.e. nvdidia or intel) using the same ioctls. > > > >> Otherwise we just repeat history and I'm not terribly inclined to keep > > > >> on > > > >> cleanup up cruft forever - one drm legacy is enough ;-) > > > >> > > > >> Jesse is the guy from our side to talk to about this. > > > >> -Daniel > > > > > > > > I am not worried about that side, the hsa foundation has pretty strict > > > > guidelines on what is hsa compliant hardware ie the hw needs to > > > > understand > > > > the pm4 packet format of radeon (well small subset of it). But of course > > > > this require hsa compliant hardware and from member i am guessing ARM > > > > Mali, > > > > ImgTech, Qualcomm, ... so unless Intel and NVidia joins hsa you will not > > > > see it for those hardware. > > > > > > > > So yes for once same ioctl would apply to different hardware. The only > > > > things > > > > that is different is the shader isa. The hsafoundation site has some pdf > > > > explaining all that but someone thought that slideshare would be a good > > > > idea > > > > personnaly i would not register to any of the website just to get the > > > > pdf. > > > > > > > > So to sumup i am ok with having a new device file that present uniform > > > > set > > > > of ioctl. It would actualy be lot easier for userspace, just open this > > > > fix > > > > device file and ask for list of compliant hardware. > > > > > > > > Then radeon kernel driver would register itself as a provider. So all > > > > ioctl > > > > decoding marshalling would be share which makes sense. > > > > > > There's also the other side namely that preparing the cp ring in > > > userspace and submitting the entire pile through a doorbell to the hw > > > scheduler isn't really hsa exclusive. And for a solid platform with > > > seamless gpu/cpu integration that means we need standard ways to set > > > gpu context priorities and get at useful stats like gpu time used by a > > > given context. > > > > > > To get there I guess intel/nvidia need to reuse the hsa subsystem with > > > the command submission adjusted a bit. Kinda like drm where kms and > > > buffer sharing is common and cs driver specific. > > > > HSA module would be for HSA compliant hardware and thus hardware would > > need to follow HSA specification which again is pretty clear on what > > the hardware need to provide. So if Intel and NVidia wants to join HSA > > i am sure they would be welcome, the more the merrier :) > > > > So i would not block HSA kernel ioctl design in order to please non HSA > > hardware especialy if at this point in time nor Intel or NVidia can > > share anything concret on the design and how this things should be setup > > for there hardware. > > > > When Intel or NVidia present their own API they should provide their > > own set of ioctl through their own platform. > > Yeah things are different enough that a uniform ioctl doesn't make > sense. If/when all the vendors decide on a single standard, we can use > that, but until then I don't see a nice way to share our doorbell & > submission scheme with HSA, and I assume nvidia is the same. > > Using HSA as a basis for non-HSA systems seems like it would add a lot > of complexity, since non-HSA hardware would have to intercept the queue > writes and manage the submission requests etc as bytecodes in the > kernel driver, or maybe as a shim layer library that wraps that stuff. > > Probably not worth the effort given that the command sets themselves > are all custom as well, driven by specific user level drivers like GL, > CL, and libva.
Well I know that - drm also has the split between shared management stuff like prime and driver private cmd submission. I still think that some common interfaces would benefit us. I want things like a gputop (and also perf counters and all that) to work the same way with the same tooling on all svm/gpgpu stuff. So a shared namespace/create for svm contexts or something like that. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
