[Bug 1777786] Re: virtio-gpu-3d.c: change virtio_gpu_fence_poll timer scale

[Thomas Huth <1777786@bugs.launchpad.net>]

Did you ever send your patch to the mailing list for discussion?

** Changed in: qemu
       Status: New => Incomplete

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Title:
  virtio-gpu-3d.c: change virtio_gpu_fence_poll timer scale

Status in QEMU:
  Incomplete

Bug description:
  We use virtio-gpu to accelerate Unigine Heaven Benchmark in VM. But we get only 5 FPS when we use AMD RX460 in our host.
  We found that guest os spent a lot of time in waiting for the return of glMapBufferRange/glUnmapBuffer commad. We suspected the host GPU was waiting for fence. So we finally change the timer of fence_poll. Afer change timer from
   ms to us， Benchmark result raise up to 22 FPS.

  From a4003af5c4fe92d55353f42767d0c45de95bb78f Mon Sep 17 00:00:00 2001
  From: chen wei <chenwei1@ruijie.com.cn>
  Date: Fri, 8 Jun 2018 17:34:45 +0800
  Subject: [PATCH] virtio-gpu:improve 3d performance greatly

    opengl function need fence support.when CPU execute opengl function, it need wait fence for synchronize GPU.
  so qemu must deal with fence timely as possible. but now the expire time of the timer to deal with fence is 10 ms.
  I think it is too long for opengl. So i will change it to 20 ns.
    Before change, when i play Unigine_Heaven 3d game with virglrenderer, the fps is 3.  atfer change the fps up to 23.

  Signed-off-by: chen wei   <chenwei1@ruijie.com.cn>
  Signed-off-by: wang qiang <qiang_w@ruijie.com.cn>
  ---
   hw/display/virtio-gpu-3d.c | 4 ++--
   1 file changed, 2 insertions(+), 2 deletions(-)

  diff --git a/hw/display/virtio-gpu-3d.c b/hw/display/virtio-gpu-3d.c
  index 3558f38..c0a5d21 100644
  --- a/hw/display/virtio-gpu-3d.c
  +++ b/hw/display/virtio-gpu-3d.c
  @@ -582,7 +582,7 @@ static void virtio_gpu_fence_poll(void *opaque)
       virgl_renderer_poll();
       virtio_gpu_process_cmdq(g);
       if (!QTAILQ_EMPTY(&g->cmdq) || !QTAILQ_EMPTY(&g->fenceq)) {
  -        timer_mod(g->fence_poll, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 10);
  +        timer_mod(g->fence_poll, qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) + 20);
       }
   }
   
  @@ -629,7 +629,7 @@ int virtio_gpu_virgl_init(VirtIOGPU *g)
           return ret;
       }
   
  -    g->fence_poll = timer_new_ms(QEMU_CLOCK_VIRTUAL,
  +    g->fence_poll = timer_new_us(QEMU_CLOCK_VIRTUAL,
                                    virtio_gpu_fence_poll, g);
   
       if (virtio_gpu_stats_enabled(g->conf)) {
  -- 
  2.7.4

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