On Fri, Jan 23, 2015 at 04:53:48PM +0100, Daniel Vetter wrote: > Yeah that's kind the big behaviour difference (at least as I see it) > between explicit sync and implicit sync: > - with implicit sync the kernel attachs sync points/requests to buffers > and userspace just asks about idle/business of buffers. Synchronization > between different users is all handled behind userspace's back in the > kernel. > > - explicit sync attaches sync points to individual bits of work and makes > them explicit objects userspace can get at and pass around. Userspace > uses these separate things to inquire about when something is > done/idle/busy and has its own mapping between explicit sync objects and > the different pieces of memory affected by each. Synchronization between > different clients is handled explicitly by passing sync objects around > each time some rendering is done. > > The bigger driver for explicit sync (besides "nvidia likes it sooooo much > that everyone uses it a lot") seems to be a) shitty gpu drivers without > proper bo managers (*cough*android*cough*) and svm, where there's simply > no buffer objects any more to attach sync information to. Actually, mesa would really like much finer granularity than at batch boundaries. Having a sync object for a batch boundary itself is very meh and not a substantive improvement on what it possible today, but being able to convert the implicit sync into an explicit fence object is interesting and lends a layer of abstraction that could make it more versatile. Most importantly, it allows me to defer the overhead of fence creation until I actually want to sleep on a completion. Also Jesse originally supporting inserting fences inside a batch, which looked interesting if impractical. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
