On Thu, Feb 11, 2016 at 02:10:19PM +0000, Tvrtko Ursulin wrote: > > On 11/02/16 13:29, Chris Wilson wrote: > >On Thu, Feb 11, 2016 at 01:20:46PM +0000, Tvrtko Ursulin wrote: > >> > >> > >>On 11/01/16 10:45, Chris Wilson wrote: > >>>By tracking the iomapping on the VMA itself, we can share that area > >>>between multiple users. Also by only revoking the iomapping upon > >>>unbinding from the mappable portion of the GGTT, we can keep that iomap > >>>across multiple invocations (e.g. execlists context pinning). > >> > >>Between the lines and from some IRC discussion it seems the goal of > >>this is to fix an address space memory leak with fbcon? > > > >The goal is to prevent an issue from hastily dropping iomappings (and > >vmappings elsewhere) when unpinning contexts. That comes into play when > >we track the ring->vma (not just track ring->vma as we do now, but can > >rely on the vma being persistent). Fixing a leak on driver unload is an > >interesting side-effect. > > > >>But I don't know fbdev so can't find who would do the unpin on the > >>VMA to allow unbind to eventually unmap it? > > > >That actually gets fixed in another patch when we teach intel_fbdev to > >actually track the VMA it allocates, as right now we deliberately leak > >it to keep the code simple. > > Ok in that case ack on the patch. > > It will need to assert on VMA being pinned I think and some minor > changes when you rebase it on top of nightly as standalone so I can > properly review it then. Had some more fun recently where the iomap was showing up again, and realised that for 64b systems we can keep a pointer to inside our dev_priv->gtt.mappable iomapping. Makes the patch a little more ugly (requires #ifdeffry) but eliminates all of the runtime iomapping overhead! However, that wasn't enough for the test case as the limitation to the mappable aperture was too severe... -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
