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: 3cfc6a20 ("iris: Fill out res->aux.possible_usages")
parent 4a0d2e28
Pipeline #67488 passed with stages
in 71 minutes and 20 seconds
......@@ -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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