Mesa (master): iris, i965: Update limits for ARB_compute_variable_group_size
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Thu May 28 04:09:30 UTC 2020
Module: Mesa
Branch: master
Commit: 78e400d4a515e8d8187259ed1287dd4671dee9ca
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=78e400d4a515e8d8187259ed1287dd4671dee9ca
Author: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>
Date: Wed May 20 23:32:18 2020 -0700
iris, i965: Update limits for ARB_compute_variable_group_size
The CS compiler now produces multiple SIMD variants, so the previous
trade-off between "always using SIMD32" and "having a smaller max
invocations" is now gone.
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5142>
---
src/gallium/drivers/iris/iris_screen.c | 36 +++++----------------------------
src/gallium/drivers/iris/iris_screen.h | 2 --
src/mesa/drivers/dri/i965/brw_context.c | 21 ++++++-------------
3 files changed, 11 insertions(+), 48 deletions(-)
diff --git a/src/gallium/drivers/iris/iris_screen.c b/src/gallium/drivers/iris/iris_screen.c
index 6695932bd0b..438ff3b4f6c 100644
--- a/src/gallium/drivers/iris/iris_screen.c
+++ b/src/gallium/drivers/iris/iris_screen.c
@@ -435,32 +435,6 @@ iris_get_shader_param(struct pipe_screen *pscreen,
}
}
-static unsigned
-get_max_threads(const struct gen_device_info *devinfo)
-{
- /* Limit max_threads to 64 for the GPGPU_WALKER command. */
- return MIN2(64, devinfo->max_cs_threads);
-}
-
-uint32_t
-iris_get_max_var_invocations(const struct iris_screen *screen)
-{
- const unsigned max_threads = get_max_threads(&screen->devinfo);
-
- /* Constants used for ARB_compute_variable_group_size. The compiler will
- * use the maximum to decide which SIMDs can be used. If we top this like
- * max_invocations, that would prevent SIMD8 / SIMD16 to be considered.
- *
- * TODO: To avoid the trade off above between having the lower maximum
- * vs. always using SIMD32, keep all three shader variants (for each SIMD)
- * and select a suitable one at dispatch time.
- */
- const uint32_t max_var_invocations =
- (max_threads >= 64 ? 8 : (max_threads >= 32 ? 16 : 32)) * max_threads;
- assert(max_var_invocations >= 512);
- return max_var_invocations;
-}
-
static int
iris_get_compute_param(struct pipe_screen *pscreen,
enum pipe_shader_ir ir_type,
@@ -468,8 +442,10 @@ iris_get_compute_param(struct pipe_screen *pscreen,
void *ret)
{
struct iris_screen *screen = (struct iris_screen *)pscreen;
+ const struct gen_device_info *devinfo = &screen->devinfo;
- const unsigned max_threads = get_max_threads(&screen->devinfo);
+ /* Limit max_threads to 64 for the GPGPU_WALKER command. */
+ const unsigned max_threads = MIN2(64, devinfo->max_cs_threads);
const uint32_t max_invocations = 32 * max_threads;
#define RET(x) do { \
@@ -499,6 +475,8 @@ iris_get_compute_param(struct pipe_screen *pscreen,
case PIPE_COMPUTE_CAP_MAX_THREADS_PER_BLOCK:
/* MaxComputeWorkGroupInvocations */
+ case PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK:
+ /* MaxComputeVariableGroupInvocations */
RET((uint64_t []) { max_invocations });
case PIPE_COMPUTE_CAP_MAX_LOCAL_SIZE:
@@ -511,10 +489,6 @@ iris_get_compute_param(struct pipe_screen *pscreen,
case PIPE_COMPUTE_CAP_SUBGROUP_SIZE:
RET((uint32_t []) { BRW_SUBGROUP_SIZE });
- case PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK:
- /* MaxComputeVariableGroupInvocations */
- RET((uint64_t []) { iris_get_max_var_invocations(screen) });
-
case PIPE_COMPUTE_CAP_MAX_MEM_ALLOC_SIZE:
case PIPE_COMPUTE_CAP_MAX_CLOCK_FREQUENCY:
case PIPE_COMPUTE_CAP_MAX_COMPUTE_UNITS:
diff --git a/src/gallium/drivers/iris/iris_screen.h b/src/gallium/drivers/iris/iris_screen.h
index 87d8a5580d7..bfc5284fc72 100644
--- a/src/gallium/drivers/iris/iris_screen.h
+++ b/src/gallium/drivers/iris/iris_screen.h
@@ -238,6 +238,4 @@ iris_is_format_supported(struct pipe_screen *pscreen,
void iris_disk_cache_init(struct iris_screen *screen);
-uint32_t iris_get_max_var_invocations(const struct iris_screen *screen);
-
#endif
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 42a0c663b6e..6ca20f24b94 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -836,22 +836,13 @@ brw_initialize_cs_context_constants(struct brw_context *brw)
ctx->Const.MaxComputeWorkGroupInvocations = max_invocations;
ctx->Const.MaxComputeSharedMemorySize = 64 * 1024;
- /* Constants used for ARB_compute_variable_group_size. The compiler will
- * use the maximum to decide which SIMDs can be used. If we top this like
- * max_invocations, that would prevent SIMD8 / SIMD16 to be considered.
- *
- * TODO: To avoid the trade off above between having the lower maximum
- * vs. always using SIMD32, keep all three shader variants (for each SIMD)
- * and select a suitable one at dispatch time.
- */
+ /* Constants used for ARB_compute_variable_group_size. */
if (devinfo->gen >= 7) {
- const uint32_t max_var_invocations =
- (max_threads >= 64 ? 8 : (max_threads >= 32 ? 16 : 32)) * max_threads;
- assert(max_var_invocations >= 512);
- ctx->Const.MaxComputeVariableGroupSize[0] = max_var_invocations;
- ctx->Const.MaxComputeVariableGroupSize[1] = max_var_invocations;
- ctx->Const.MaxComputeVariableGroupSize[2] = max_var_invocations;
- ctx->Const.MaxComputeVariableGroupInvocations = max_var_invocations;
+ assert(max_invocations >= 512);
+ ctx->Const.MaxComputeVariableGroupSize[0] = max_invocations;
+ ctx->Const.MaxComputeVariableGroupSize[1] = max_invocations;
+ ctx->Const.MaxComputeVariableGroupSize[2] = max_invocations;
+ ctx->Const.MaxComputeVariableGroupInvocations = max_invocations;
}
}
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