On Fri, Sep 09, 2016 at 09:32:50AM +0100, Tvrtko Ursulin wrote: > > On 08/09/16 17:40, Chris Wilson wrote: > >On Thu, Sep 08, 2016 at 04:12:55PM +0100, Tvrtko Ursulin wrote: > >>From: Tvrtko Ursulin <tvrtko.ursu...@intel.com> > >> > >>This removes the usage of intel_ring_emit in favour of > >>directly writing to the ring buffer. > > > >I have the same patch! But I called it out, for historical reasons. > > Yes I know we talked about it in the past but I did not think you > will find time to actually write it amongst all the other things. > > >Oh, except mine uses out[0]...out[N] because gcc prefers that over > >*out++ = ... > > It copes just fine with the latter here, for example: > > *rbuf++ = cmd; > *rbuf++ = I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT; > *rbuf++ = 0; /* upper addr */ > *rbuf++ = 0; /* value */ > > Is: > > 3e9: 89 10 mov %edx,(%rax) > 3eb: c7 40 04 04 01 00 00 movl $0x104,0x4(%rax) > 3f2: c7 40 08 00 00 00 00 movl $0x0,0x8(%rax) > 3f9: c7 40 0c 00 00 00 00 movl $0x0,0xc(%rax)
Great. Last time we had a conversation about this, and when we looked at constructing batchbuffers in userpspace, gcc was still generating two instuctions (*ptr followed by ptr++) rather than emitting the mov to a fixed offset for that sequence. > >plus an ealier > > > > drivers/gpu/drm/i915/i915_gem_request.c | 26 ++--- > > drivers/gpu/drm/i915/intel_lrc.c | 121 ++++++++--------------- > > drivers/gpu/drm/i915/intel_ringbuffer.c | 168 > > +++++++++++--------------------- > > drivers/gpu/drm/i915/intel_ringbuffer.h | 10 +- > > 4 files changed, 112 insertions(+), 213 deletions(-) > > > >since I wanted parts of it for emitting timelines. > > Ok what do you want to do? I have plans to use that particular patch soon, but updating intel_ring_begin() itself is a long way down my list. Given that you have a patch ready, let's keep going. I'm just curious as to what I did differently to trim off the extra lines (probably intel_ring_advance()). The other thing I did was to relax the restriction to only emit in qword aligned packets (by fixing up the tail for qword alignment on sealing the request). Also, I would rather the function be expressed as operating on the request, i915_gem_request_emit() was my choice. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
