[Mesa-dev] [PATCH] intel/compiler/gen10: Disable push constants.

[Ben Widawsky]

On 17-12-18 15:23:11, Antognolli, Rafael wrote:
>We still have gpu hangs on Cannonlake when using push constants, so
>disable them for now until we have a proper fix for these hangs.
>
>v2: Add warning message when creating context too.
>
>Signed-off-by: Rafael Antognolli <rafael.antognolli at intel.com>
>Cc: Ben Widawsky <ben at bwidawsk.net>
>Cc: Kenneth Graunke <kenneth at whitecape.org>

Since this improves the current situation by enabling more workloads to be run
by folks with these platforms, and we don't regress any of the conformance
suites, this is:

Reviewed-by: Ben Widawsky <ben at bwidawsk.net>

I'd go as far as to suggest this for stable, but I know there's a lot of
heartburn around that.

>---
> src/intel/compiler/brw_fs.cpp           | 9 +++++++++
> src/mesa/drivers/dri/i965/brw_context.c | 7 +++++++
> 2 files changed, 16 insertions(+)
>
>diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
>index 3717c50e32a..6d9f0eccb29 100644
>--- a/src/intel/compiler/brw_fs.cpp
>+++ b/src/intel/compiler/brw_fs.cpp
>@@ -2096,6 +2096,15 @@ fs_visitor::assign_constant_locations()
>    if (subgroup_id_index >= 0)
>       max_push_components--; /* Save a slot for the thread ID */
>
>+   /* FIXME: We currently have some GPU hangs that happen apparently when using
>+    * push constants. Since we have no solution for such hangs yet, just
>+    * go ahead and use pull constants for now.
>+    */
>+   if (devinfo->gen == 10 && compiler->supports_pull_constants) {
>+      compiler->shader_perf_log(log_data, "Disabling push constants.");
>+      max_push_components = 0;
>+   }
>+
>    /* We push small arrays, but no bigger than 16 floats.  This is big enough
>     * for a vec4 but hopefully not large enough to push out other stuff.  We
>     * should probably use a better heuristic at some point.
>diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
>index 126c187f629..b555f7bfdf1 100644
>--- a/src/mesa/drivers/dri/i965/brw_context.c
>+++ b/src/mesa/drivers/dri/i965/brw_context.c
>@@ -1022,6 +1022,13 @@ brwCreateContext(gl_api api,
>       return false;
>    }
>
>+   if (devinfo->gen == 10) {
>+      fprintf(stderr,
>+              "WARNING: i965 does not fully support Gen10 yet.\n"
>+              "Instability or lower performance might occur.\n");
>+
>+   }
>+
>    brw_init_state(brw);
>
>    intelInitExtensions(ctx);
>-- 
>2.14.3
>