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

Bug #1777786 reported by Qiang Wang
This bug affects 1 person
Affects Status Importance Assigned to Milestone

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 <email address hidden>
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 <email address hidden>
Signed-off-by: wang qiang <email address hidden>
 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)
     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)) {

Revision history for this message
Qiang Wang (wqlxx) wrote :
Revision history for this message
Thomas Huth (th-huth) wrote :

Please don't use the bug tracker for providing patches, and send it to the mailing list instead, see:

Revision history for this message
Thomas Huth (th-huth) wrote :

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

Changed in qemu:
status: New → Incomplete
Revision history for this message
Launchpad Janitor (janitor) wrote :

[Expired for QEMU because there has been no activity for 60 days.]

Changed in qemu:
status: Incomplete → Expired
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