On Thu, Apr 04, 2013 at 04:41:46PM -0700, Ben Widawsky wrote: > These patches implement full context reference counting. In the patch that > actually adds the reference counting, I explain why I think Mika's reference > counting isn't sufficient for me. Please see/respond to that patch if you > disagree. > > Almost all of the actual work occurs in: > "drm/i915: Store last context instead of the obj" > > This work is preliminary work for what I'm actually doing at the moment which > is proper PPGTT support. The patches split off quite nicely here, so I'm > submitting it for review separately. I believe these patches provide a superset > of the functionality needed by Mika for ARB_Robustness. > > The primary reason I want to track context destruction is for PPGTT support > we'd like to teardown ppgtt state when a context goes away, but can only do so > when we're absolutely certain those PTEs are no longer needed. In my design, > I've made a 1:1 relationship with context->ppgtt, and so refcounting the > context makes sense there. The crux of the solution here is to store the > context pointer in the object that backs it. I could probably use that alone to > solve my problem, but I've gone a bit further and also stored the last context > in the ring, instead of the last context object. I can't show code yet, but > I believe there are a couple of other niceties to having the last context, and > not an object. I sent the wrong version of this text. What I meant is, the crux of the solution is reference counting + storing the context pointer in the object. I believe I am not /required/ to store the last_context as I've done. > > There is at least one sticking point in this patch series, which is the > aforementioned storing of the context in the object backs the context. That > patch has been rejected before. I'm open to other ways to handle this. > At the very least, I require being able to teardown PPGTT when a context > dies. > > For reference, here is the last time the patch was shot down: > http://lists.freedesktop.org/archives/intel-gfx/2012-June/thread.html#18000 > > Ben Widawsky (7): > drm/i915: Mark context switch likely > drm/i915: Move context special case to get() > drm/i915: Make object aware that it backs a context > drm/i915: Better context messages > drm/i915: Track context status > drm/i915: Store last context instead of the obj > drm/i915: Print all contexts in debugfs > > drivers/gpu/drm/i915/i915_debugfs.c | 30 +++++++- > drivers/gpu/drm/i915/i915_drv.h | 10 ++- > drivers/gpu/drm/i915/i915_gem.c | 2 + > drivers/gpu/drm/i915/i915_gem_context.c | 127 ++++++++++++++++++++++---------- > drivers/gpu/drm/i915/intel_ringbuffer.h | 2 +- > 5 files changed, 129 insertions(+), 42 deletions(-) > > -- > 1.8.2 > -- Ben Widawsky, Intel Open Source Technology Center
