Am 11.10.2013 01:15, schrieb Marek Olšák:
On Thu, Oct 10, 2013 at 6:38 PM, Vadim Girlin <vadimgir...@gmail.com> wrote:
On 10/10/2013 08:10 PM, Christian König wrote:
Am 10.10.2013 18:02, schrieb Vadim Girlin:
On 10/10/2013 02:11 PM, Michel Dänzer wrote:
On Don, 2013-10-10 at 12:49 +0400, Vadim Girlin wrote:
Currently it's hardcoded in the shader, so every change requires
compilation of the shader variant, killing the performance
in Serious Sam 3 and probably other apps.
This patch passes alpha_ref in the user sgpr and removes it from
the shader key.
Signed-off-by: Vadim Girlin <vadimgir...@gmail.com>
Reviewed-by: Michel Dänzer <michel.daen...@amd.com>
I presume this causes no regressions with piglit quick.tests.
Yes, there are no regressions with piglit. Thanks for reviewing.
By the way, I'm also not sure if this is the right way of doing it,
especially if we'll need to pass more parameters for any new features.
Possibly some other ways could be more preferable, e.g. to put it with
any other data that we may need in the future into internal const
buffer (like we do in r600g for clip planes etc), or maybe there are
other ways on SI that I'm not aware of yet?
That strongly depends on how often we use a parameter. The docs speak of
a penalty associated with loading each SGPR so we should try to use as
less as possible, but loading something from constant space is also
costly without proper support for the constant IB.
By the way, AFAICS some SGPR inputs are often not used at all in the
shaders, I guess we might want to use per-shader mapping of parameters to
SGPRs so that we'll only load actually used values for each shader. Compiler
will need to pack required input SGPRs to lowest indices and provide the
parameter->SGPR map to the driver. OTOH this would slightly increase the
amount of driver's work, so I'm not really sure yet if it's worth it, looks
like we already have a pretty significant overhead.
I think this an interesting optimization. Most of our overhead is
elsewhere anyway. The only overhead added here would only be in the
bind_xx_shader function, because all the shader user-data registers
would have to be updated. Note that some of the input SGPRs are
already declared conditionally, e.g. the SGPRs containing streamout
state.
Indeed, but the having the streamout optionally currently only works
because it is the last entry in the list.
I think the first step should be to have only one pointer for samplers
and resources or maybe even for samplers, resources and constants. We
should take care that the offset still fits into the SMRD instruction,
but apart from that I don't see why we need more than one pointer for them.
Basically we just need to allocate SGPRs for everything the shaders use
(samplers, resources, constants, vertex buffers, stream out buffers
etc...) and fill each SGPR just before issuing the draw call. A bitmask
of whats used and a single command for filling all SGPRs in order should
be pretty much sufficient.
Christian.
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