Re: [Qemu-devel] [PATCH] virtio_gpu_3d: make it possible to configure the fence poll time

[Marc-André Lureau]

Hi

On Thu, May 23, 2019 at 3:27 PM Gert Wollny <address@hidden> wrote:
>
> The default fence poll time of 10ms (100 Hz) is sufficent for normal
> work loads, but if one wants to play games within the virtual machine
> this value might be too high, so make it possible to configure this
> value by using the environment variable QEMU_VIRGL_POLL_FREQ where the
> poll is given in Hz. To acommodate higher poll frequencies also change
> the timer to use micro seconds as base instead of milliseconds.
>
>

This is what VIRGL_RENDERER_THREAD_SYNC helps with. You don't need to
do regular polling, but I think it is currently limited to
Linux/eventfd only.

fwiw, vhost-user-gpu uses it.


> Signed-off-by: Gert Wollny <address@hidden>
> ---
>  hw/display/virtio-gpu-3d.c     | 18 ++++++++++++++++--
>  include/hw/virtio/virtio-gpu.h |  1 +
>  2 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/hw/display/virtio-gpu-3d.c b/hw/display/virtio-gpu-3d.c
> index 5ee3566ae0..120e593e76 100644
> --- a/hw/display/virtio-gpu-3d.c
> +++ b/hw/display/virtio-gpu-3d.c
> @@ -17,6 +17,7 @@
>  #include "trace.h"
>  #include "hw/virtio/virtio.h"
>  #include "hw/virtio/virtio-gpu.h"
> +#include "qemu/cutils.h"
>
>  #ifdef CONFIG_VIRGL
>
> @@ -580,7 +581,8 @@ 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) + 1);
> +        timer_mod(g->fence_poll, qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) +
> +                                 g->fence_poll_timeout);
>      }
>  }
>
> @@ -605,13 +607,25 @@ void virtio_gpu_virgl_reset(VirtIOGPU *g)
>  int virtio_gpu_virgl_init(VirtIOGPU *g)
>  {
>      int ret;
> +    const char *val;
>
>      ret = virgl_renderer_init(g, 0, &virtio_gpu_3d_cbs);
>      if (ret != 0) {
>          return ret;
>      }
>
> -    g->fence_poll = timer_new_ms(QEMU_CLOCK_VIRTUAL,
> +    g->fence_poll_timeout = 10000; /* default 10 ms */
> +    val = getenv("QEMU_VIRGL_POLL_FREQ");
> +    if (val) {
> +        unsigned long long poll_freq;
> +        if (parse_uint_full(val, &poll_freq, 10) || poll_freq > UINT32_MAX) {
> +            fprintf(stderr, "VIRGL_POLL_FREQ: Invalid integer `%s'\n", val);
> +            exit(1);
> +        }
> +        g->fence_poll_timeout = 1000000 / (uint32_t)poll_freq;
> +    }
> +
> +    g->fence_poll = timer_new_us(QEMU_CLOCK_VIRTUAL,
>                                   virtio_gpu_fence_poll, g);
>
>      if (virtio_gpu_stats_enabled(g->conf)) {
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index 60425c5d58..a9e03b25aa 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -116,6 +116,7 @@ typedef struct VirtIOGPU {
>      bool renderer_reset;
>      QEMUTimer *fence_poll;
>      QEMUTimer *print_stats;
> +    uint32_t fence_poll_timeout;
>
>      uint32_t inflight;
>      struct {
> --
> 2.20.1
>
>


-- 
Marc-André Lureau