Mesa (staging/19.2): iris: Disable CCS_E for 32-bit floating point textures.
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Tue Oct 1 22:31:05 UTC 2019
Module: Mesa
Branch: staging/19.2
Commit: d4dab05a0932e00b507318ae74df81ddbb50c4c1
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=d4dab05a0932e00b507318ae74df81ddbb50c4c1
Author: Kenneth Graunke <kenneth at whitecape.org>
Date: Thu Aug 29 00:38:15 2019 -0700
iris: Disable CCS_E for 32-bit floating point textures.
A while back, Michael Larabel noticed that Paraview's Wavelet Volume
case runs significantly slower on iris than i965. It turns out this
is because we enable CCS_E for 32-bit floating point formats, while
i965 disables it, with an oblique comment saying that we benchmarked
it (on what exactly?) and determined that it was a loss.
Paraview uses both R32_FLOAT and R32G32B32A32_FLOAT, and I observed
large framerate drops when enabling CCS_E for either format. However,
several other benchmarks (Aztec Ruins, many Synmark cases) use 16-bit
floating point formats, with no apparent ill effects.
So, disable compression for 32-bit float formats for now, but leave it
enabled for 16-bit float formats as they seem to be working fine.
Improves performance in Paraview's Wavelet Volume test by 62% on a
Skylake GT4e.
Fixes: 3cfc6a207bd ("iris: Fill out res->aux.possible_usages")
(cherry picked from commit a0a93763fba18ce3c9c90a0f939005f0b594e27c)
---
src/gallium/drivers/iris/iris_resource.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/src/gallium/drivers/iris/iris_resource.c b/src/gallium/drivers/iris/iris_resource.c
index a539d090ebe..c13356d1c83 100644
--- a/src/gallium/drivers/iris/iris_resource.c
+++ b/src/gallium/drivers/iris/iris_resource.c
@@ -628,6 +628,28 @@ supports_ccs(const struct gen_device_info *devinfo,
return true;
}
+static bool
+want_ccs_e_for_format(const struct gen_device_info *devinfo,
+ enum isl_format format)
+{
+ if (!isl_format_supports_ccs_e(devinfo, format))
+ return false;
+
+ const struct isl_format_layout *fmtl = isl_format_get_layout(format);
+
+ /* CCS_E seems to significantly hurt performance with 32-bit floating
+ * point formats. For example, Paraview's "Wavelet Volume" case uses
+ * both R32_FLOAT and R32G32B32A32_FLOAT, and enabling CCS_E for those
+ * formats causes a 62% FPS drop.
+ *
+ * However, many benchmarks seem to use 16-bit float with no issues.
+ */
+ if (fmtl->channels.r.bits == 32 && fmtl->channels.r.type == ISL_SFLOAT)
+ return false;
+
+ return true;
+}
+
static struct pipe_resource *
iris_resource_create_for_buffer(struct pipe_screen *pscreen,
const struct pipe_resource *templ)
@@ -765,7 +787,7 @@ iris_resource_create_with_modifiers(struct pipe_screen *pscreen,
res->aux.possible_usages |= 1 << ISL_AUX_USAGE_HIZ;
} else if (likely(!(INTEL_DEBUG & DEBUG_NO_RBC)) &&
supports_ccs(devinfo, &res->surf)) {
- if (isl_format_supports_ccs_e(devinfo, res->surf.format))
+ if (want_ccs_e_for_format(devinfo, res->surf.format))
res->aux.possible_usages |= 1 << ISL_AUX_USAGE_CCS_E;
if (isl_format_supports_ccs_d(devinfo, res->surf.format))
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