[PATCH] drm/xe/ptl: Disable null query for anyhit shader

[Matt Roper]

On Wed, May 07, 2025 at 10:50:20AM -0300, Gustavo Sousa wrote:
> Quoting Nitin Gote (2025-05-07 09:44:37-03:00)
> >For PTL, disable null query for anyhit shader as it
> >currently does not bring any performance benefits.
> >Quite the contrary, disabling the mechanism brings a
> >small but consistent perf uplift.
> >
> >Signed-off-by: Nitin Gote <nitin.r.gote at intel.com>
> 
> This seems to match the requirements for Xe3 according to the
> description of RT_CTL. So

Doesn't the description (on bspec 57496) indicate that it applies to
everything Xe2 and beyond?  I don't see anything there about Xe3
specifically.  In that case something like GRAPHICS_VERSION_RANGE(2000,
XE_RTP_END_VERSION_UNDEFINED) would be more accurate reflection of that
note.

But that bspec page also indicates that '1' is already the hardware
default value on all such platforms, so this patch doesn't seem
necessary if the spec is correct.


Matt

> 
> Reviewed-by: Gustavo Sousa <gustavo.sousa at intel.com>
> 
> However, we usually have entries in Bspec 72161 for this kind of stuff.
> Could we get that page updated with a proper entry for this tuning,
> please?
> 
> Also, I would use "drm/xe/xe3:" in the commit subject, since this is
> applicable to the Xe3 IP and not necessarily specific to the platform.
> 
> --
> Gustavo Sousa
> 
> >---
> > drivers/gpu/drm/xe/xe_tuning.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> >diff --git a/drivers/gpu/drm/xe/xe_tuning.c b/drivers/gpu/drm/xe/xe_tuning.c
> >index 49ddbda7cdef..6f2f3428b12e 100644
> >--- a/drivers/gpu/drm/xe/xe_tuning.c
> >+++ b/drivers/gpu/drm/xe/xe_tuning.c
> >@@ -98,6 +98,11 @@ static const struct xe_rtp_entry_sr engine_tunings[] = {
> >                        ENGINE_CLASS(RENDER)),
> >           XE_RTP_ACTIONS(SET(SAMPLER_MODE, INDIRECT_STATE_BASE_ADDR_OVERRIDE))
> >         },
> >+        { XE_RTP_NAME("Tuning: Disable NULL query for Anyhit Shader"),
> >+          XE_RTP_RULES(GRAPHICS_VERSION_RANGE(3000, 3001),
> >+                       FUNC(xe_rtp_match_first_render_or_compute)),
> >+          XE_RTP_ACTIONS(SET(RT_CTRL, DIS_NULL_QUERY))
> >+        },
> > };
> > 
> > static const struct xe_rtp_entry_sr lrc_tunings[] = {
> >-- 
> >2.25.1
> >

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation