On Tue, Nov 25, 2014 at 02:30:55PM +0000, Daniel, Thomas wrote: > > -----Original Message----- > > From: daniel.vetter@xxxxxxxx [mailto:daniel.vetter@xxxxxxxx] On Behalf Of > > Daniel Vetter > > Sent: Thursday, November 20, 2014 12:51 PM > > To: Chris Wilson; Daniel, Thomas; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; akash goel > > (akash.goels@xxxxxxxxx) > > Subject: Re: [PATCH] drm/i915: Don't pin LRC in GGTT when > > dumping in debugfs > > > > On Thu, Nov 20, 2014 at 1:28 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > wrote: > > >> Can you identify any situation where the pages may go away? > > > > > > Anytime you trigger an allocation, the system may reap any objects > > > pages. It will even steal the dev->struct_mutex. To protect against > > > the shrinker you have to call pin_pages(). Here, there are no > > > allocations inside the loop and so you don't need to worry about the > > > shrinker stealing your pages. > > > > Hm actually I think better safe than sorry here. At least I have > > (again) completely forgotten about our dear shrinker ... > > -Daniel > > Does this discussion count as a review? What was the conclusion - do I need to make a version without pinning or is it better safe than sorry? To bring it full circle: >> LRC object does not need to be mapped into the GGTT when dumping. Just use >> pin_pages. A side-effect of this patch is that a compiler warning goes away >> (not checking return value of i915_gem_obj_ggtt_pin). > Please explain why you need to pin the pages. In particular, explain why just calling pin_pages() doesn't do what you want. And then afterwards you can leave a note in the commitlog why you use pin_pages() as overkill. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
