<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [PNV Bisected]igt/gem_exec_big fails" href="https://bugs.freedesktop.org/show_bug.cgi?id=88191#c1">Comment # 1</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [PNV Bisected]igt/gem_exec_big fails" href="https://bugs.freedesktop.org/show_bug.cgi?id=88191">bug 88191</a> from <a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> Chris Wilson</a> <pre>So far it looks like it has uncovered a nasty coherency issue between pwrite + set-to-domain + relocate + pread. Forcing pwrite to use GTT, makes it work, as does removing the user set-to-domain. It also seems to be timing dependent (but it fails quite reproducibly), adding printk also makes it work. Throwing i915_gem_chipset_flush() around is not sufficient. But... diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index c7f4048..831cef2 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -332,6 +332,8 @@ relocate_entry_gtt(struct drm_i915_gem_object *obj, if (ret) return ret; + mb(); + /* Map the page containing the relocation we're going to perform. */ offset = i915_gem_obj_ggtt_offset(obj); offset += reloc->offset; @@ -355,6 +357,7 @@ relocate_entry_gtt(struct drm_i915_gem_object *obj, io_mapping_unmap_atomic(reloc_page); + mb(); return 0; } crazily enough does. And notably diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index c7f4048..3da285a 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -880,7 +880,7 @@ vmas_move_to_rq(struct eb_vmas *eb, i915_gem_chipset_flush(rq->i915); if (flush_domains & I915_GEM_DOMAIN_GTT) - wmb(); + mb(); /* 2: invalidate the caches from this ring after emitting semaphores */ ret = i915_request_emit_flush(rq, I915_INVALIDATE_CACHES); does not. Hmm.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are on the CC list for the bug.</li> </ul> </body> </html>