[Mesa-dev] [PATCH 7/8] radeonsi: always put persistent buffers into GTT on radeon

[Marek Olšák]

On Mon, Jun 11, 2018 at 6:54 AM, Michel Dänzer <michel at daenzer.net> wrote:

> On 2018-06-09 05:16 AM, Marek Olšák wrote:
> > From: Marek Olšák <marek.olsak at amd.com>
> >
> > This improves performance for certain games.
> >
> > Cc: 18.1 <mesa-stable at lists.freedesktop.org>
> > ---
> >  src/gallium/drivers/radeonsi/si_buffer.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/gallium/drivers/radeonsi/si_buffer.c
> b/src/gallium/drivers/radeonsi/si_buffer.c
> > index 2d68edc3404..0546fa9d336 100644
> > --- a/src/gallium/drivers/radeonsi/si_buffer.c
> > +++ b/src/gallium/drivers/radeonsi/si_buffer.c
> > @@ -144,22 +144,26 @@ void si_init_resource_fields(struct si_screen
> *sscreen,
> >       if (res->b.b.target == PIPE_BUFFER &&
> >           res->b.b.flags & (PIPE_RESOURCE_FLAG_MAP_PERSISTENT |
> >                             PIPE_RESOURCE_FLAG_MAP_COHERENT)) {
> >               /* Use GTT for all persistent mappings with older
> >                * kernels, because they didn't always flush the HDP
> >                * cache before CS execution.
> >                *
> >                * Write-combined CPU mappings are fine, the kernel
> >                * ensures all CPU writes finish before the GPU
> >                * executes a command stream.
> > +              *
> > +              * radeon doesn't have good BO move throttling, so put all
> > +              * persistent buffers into GTT to prevent VRAM CPU page
> faults.
> >                */
> > -             if (!sscreen->info.kernel_flushes_hdp_before_ib)
> > +             if (!sscreen->info.kernel_flushes_hdp_before_ib ||
> > +                 sscreen->info.drm_major == 2)
> >                       res->domains = RADEON_DOMAIN_GTT;
>
> sscreen->info.kernel_flushes_hdp_before_ib is always true with amdgpu,
> so this could be simplified to
>
>         if (sscreen->info.drm_major == 2)
>

It might not be true for a hypothetical third and fourth winsys. :)

Marek
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