On Fri, Dec 19, 2014 at 02:29:57PM +0100, Daniel Vetter wrote: > On Fri, Dec 19, 2014 at 01:10:40PM +0000, Chris Wilson wrote: > > On Fri, Dec 19, 2014 at 11:13:51AM +0100, Daniel Vetter wrote: > > > On Fri, Dec 19, 2014 at 08:50:09AM +0000, Chris Wilson wrote: > > > > On Fri, Dec 19, 2014 at 09:37:52AM +0100, Daniel Vetter wrote: > > > > > On Fri, Dec 19, 2014 at 08:31:03AM +0000, Chris Wilson wrote: > > > > > > On Thu, Dec 18, 2014 at 10:16:22PM +0100, Daniel Vetter wrote: > > > > > > > On Thu, Dec 18, 2014 at 05:09:57PM +0000, Michel Thierry wrote: > > > > > > > > This new version tries to remove as many unnecessary changes as possible from > > > > > > > > the previous RFC. > > > > > > > > > > > > > > > > For GEN8, it has also been extended to work in logical ring submission (lrc) > > > > > > > > mode, as it will be the preferred mode of operation. > > > > > > > > I also tried to update the lrc code at the same time the ppgtt refactoring > > > > > > > > occurred, leaving only one patch that is exclusively for lrc. > > > > > > > > > > > > > > > > This list can be seen in 3 parts: > > > > > > > > [01-10] Include code rework for PPGTT (all GENs). > > > > > > > > [11-14] Adds page table allocation for GEN6/GEN7 > > > > > > > > [15-24] Enables dynamic allocation in GEN8. It is enabled for both legacy > > > > > > > > and execlist submission modes. > > > > > > > > > > > > > > > > Ben Widawsky (23): > > > > > > > > drm/i915: Add some extra guards in evict_vm > > > > > > > > drm/i915/trace: Fix offsets for 64b > > > > > > > > drm/i915: Rename to GEN8_LEGACY_PDPES > > > > > > > > drm/i915: Setup less PPGTT on failed pagedir > > > > > > > > drm/i915/gen8: Un-hardcode number of page directories > > > > > > > > drm/i915: Range clearing is PPGTT agnostic > > > > > > > > drm/i915: page table abstractions > > > > > > > > drm/i915: Complete page table structures > > > > > > > > drm/i915: Create page table allocators > > > > > > > > drm/i915: Track GEN6 page table usage > > > > > > > > drm/i915: Extract context switch skip logic > > > > > > > > drm/i915: Track page table reload need > > > > > > > > drm/i915: Initialize all contexts > > > > > > > > drm/i915: Finish gen6/7 dynamic page table allocation > > > > > > > > drm/i915/bdw: Use dynamic allocation idioms on free > > > > > > > > drm/i915/bdw: pagedirs rework allocation > > > > > > > > drm/i915/bdw: pagetable allocation rework > > > > > > > > drm/i915/bdw: Update pdp switch and point unused PDPs to scratch page > > > > > > > > drm/i915: num_pd_pages/num_pd_entries isn't useful > > > > > > > > drm/i915: Extract PPGTT param from pagedir alloc > > > > > > > > drm/i915/bdw: Split out mappings > > > > > > > > drm/i915/bdw: begin bitmap tracking > > > > > > > > drm/i915/bdw: Dynamic page table allocations > > > > > > > > > > > > > > > > Michel Thierry (1): > > > > > > > > drm/i915/bdw: Dynamic page table allocations in lrc mode > > > > > > > > > > > > > > Ok, I've tried to read through this series again and I definitely see a > > > > > > > bit clearer, but it's still fairly confusing to me. I think that's just > > > > > > > the long history of this patch series - often it seems to do something and > > > > > > > then undo it again in some later patch. Which doesn't help understanding > > > > > > > it. > > > > > > > > > > > > > > I've replied with a few comments. Imo the way forward with this is to > > > > > > > read, understand and review it from the beginning and merge while that's > > > > > > > happening. It will probably take a few rounds until all the confusion is > > > > > > > cleared up and we've reached the last patch. > > > > > > > > > > > > I honestly think this is starting off in the wrong direction. The first > > > > > > task, imo, is to make the current PD swappable. Then, we can introduce > > > > > > infrastructure to do deferred page allocation, hopefully combining with > > > > > > an approach to allow userspace to similarly defer their page allocation. > > > > > > > > > > Thus far things started to blow up because we need a bit too much memory > > > > > in testcases so we need this. We'll probably need the pd swapping > > > > > eventually, too. But only on gen7, and atm it doesn't look good for ppgtt > > > > > on gen7 still. Given that I think the priorities are right for now. > > > > > > > > > > But yeah we need to keep this in mind for gen7 full ppgtt. > > > > > > > > Certainly making the toplevel PD swappable on BDW is less of a priority, > > > > since that should also be already done as part of execlists (and it is so > > > > much smaller). I would like to see the gen6/7 deferred allocation > > > > removed from this series, as I still consider it to be the wrong initial > > > > approach (and making the current gen7 full-ppgtt swappable is rather > > > > trivial). > > > > > > I don't understand why you'd want to hold up the delayed pagetable alloc > > > until the pd is evictable. Imo these are fairly orthogoanl issues: pd > > > eviction tries to make ggtt space reclaimable, while deferred pagetable > > > alloc ensure that we don't alloc 2M of pagetables (which are system > > > memory) in the lower level when not needed. > > > > There is only one level of PD on ivb, and it is 2M of pinned memory. > > I think we have a mixup of nomeclatura here. The thing that takes 512x4k > on ivb are imo the pagetables, whereas the page directory entries are the > 512 entries in the global gtt table. We can't swap those entries out, but > we could evict them from the ggtt. Page Directory vs Page Directory Entries. Of course they can be written to a swapfile when idle and repinned before use. > > > So imo we can go ahead with > > > both in parallel. There might be some minor conflicts between this series > > > and making pd ggtt blocks evictable around pd reloading, but noting > > > fundamental. > > > > The trivial way to make it work, is to make the PD an obj. That then > > ties into the existing vma/obj management and debug/error > > infrastructure. Having deferred allocation for objects is also on the > > wishlist. > > > > > Or are we talking past each another? Just wondering since you call it > > > "swappable pd" and I can't really think of a way we could swap out pds to > > > disk on gen7 (they just block ggtt space which can't be used for real ptes > > > any more). > > > > Of course we can swap the inactive page directory tables. > > See above, I don't think we can. Furthermore the vm doesn't bother with > making page tables or directories reclaimable afaik (we don't need to swap > them out, we can simply free them when everything in them is evicted). So > I don't think that's worth the bother. > > If we really have a problem with pagetables we can add it to the oom > shrinker: Walking all vms and dropping all pagetables for completely empty > vms would be conceptually really simple. And there shouldn't be anything > left really when all objects are evicted for a ppgtt vm. It is trivial to do so right now. If you look at the problem, you will see that is a requirement to do things like execlists correctly, rather than the current hodgepodge. In addition, we get a host of debugging insight for free. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
