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

[Gert Wollny]

Am Donnerstag, den 23.05.2019, 16:01 +0200 schrieb 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.

As far as I can see only vtest uses this, not qemu. 

> 
> fwiw, vhost-user-gpu uses it.

Yeah, I tested it on Intel, but AFAICS this hasn't landed yet, no? OTOH
the drm calls were only implemented for Intel, and I have no idea how
to implement this for other hardware, like e.g. radeonsi, or even the
Nvidia blob ...

Best, 
Gert 


> 
> 
> > 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
> > 
> > 
> 
>