On Thu, Jun 29, 2017 at 08:41:53AM +0200, Gerd Hoffmann wrote: > Hi, > > > > Does gvt track the live cycle of all dma-bufs it has handed out? > > > > The V9 implementation does track the dma-bufs' live cycle. The > > original idea was that leaving the dma-bufs' live cycle management to > > user mode. > > That is still the case, user space decides which dma-bufs it'll go keep > cached. But kernel space can see what user space is doing, so there is > no need to explicitly tell the kernel whenever a cached dma-buf exists > or not. We do the same trick in drm_prime.c, keeping a cache of exported dma-buf around for re-exporting. Since for prime sharing the use-case is almost always re-importing as a drm gem buffer again we can then on re-import also tell userspace whether it already has that buffer in it's userspace buffer manager, but that's an additional optimization. With plain dma-buf we could achieve the same by wiring up a real stat() implementation with unique inode numbers (atm they all share the anon_inode singleton). But thus far no one asked for that. btw I'm lost a bit in the discussion (was on vacation), but I think all the concerns I've noticed with the initial rfc have been raised already, so things look good. I'll check the next rfc once that shows up. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
