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ir3: Assert that we cannot have enough concurrent waves for CS with barrier 

If we have a compute shader that has a big workgroup, a barrier, and
a branchstack which limits max_waves - this may result in a situation
when we cannot run concurrently all waves of the workgroup, which
would lead to a hang.

Blob just explodes in such case.

Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14110>
This commit is contained in:
Danylo Piliaiev 2021-12-07 16:43:21 +02:00 committed by Marge Bot
parent 9ed4d49c97
commit 3792fbfcf6
1 changed files with 36 additions and 18 deletions
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54
src/freedreno/ir3/ir3.c
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@ -177,24 +177,6 @@ ir3_get_reg_independent_max_waves(struct ir3_shader_variant *v,
const struct ir3_compiler *compiler = v->shader->compiler;
unsigned max_waves = compiler->max_waves;
/* If this is a compute shader, compute the limit based on shared size */
if ((v->type == MESA_SHADER_COMPUTE) ||
(v->type == MESA_SHADER_KERNEL)) {
/* Shared is allocated in chunks of 1k */
unsigned shared_per_wg = ALIGN_POT(v->shared_size, 1024);
if (shared_per_wg > 0 && !v->local_size_variable) {
unsigned wgs_per_core = compiler->local_mem_size / shared_per_wg;
unsigned threads_per_wg =
v->local_size[0] * v->local_size[1] * v->local_size[2];
unsigned waves_per_wg =
DIV_ROUND_UP(threads_per_wg, compiler->threadsize_base *
(double_threadsize ? 2 : 1) *
compiler->wave_granularity);
max_waves = MIN2(max_waves, waves_per_wg * wgs_per_core *
compiler->wave_granularity);
}
}
/* Compute the limit based on branchstack */
if (v->branchstack > 0) {
unsigned branchstack_max_waves = compiler->branchstack_size /
@ -203,6 +185,42 @@ ir3_get_reg_independent_max_waves(struct ir3_shader_variant *v,
max_waves = MIN2(max_waves, branchstack_max_waves);
}
/* If this is a compute shader, compute the limit based on shared size */
if ((v->type == MESA_SHADER_COMPUTE) ||
(v->type == MESA_SHADER_KERNEL)) {
unsigned threads_per_wg =
v->local_size[0] * v->local_size[1] * v->local_size[2];
unsigned waves_per_wg =
DIV_ROUND_UP(threads_per_wg, compiler->threadsize_base *
(double_threadsize ? 2 : 1) *
compiler->wave_granularity);
/* Shared is allocated in chunks of 1k */
unsigned shared_per_wg = ALIGN_POT(v->shared_size, 1024);
if (shared_per_wg > 0 && !v->local_size_variable) {
unsigned wgs_per_core = compiler->local_mem_size / shared_per_wg;
max_waves = MIN2(max_waves, waves_per_wg * wgs_per_core *
compiler->wave_granularity);
}
/* If we have a compute shader that has a big workgroup, a barrier, and
* a branchstack which limits max_waves - this may result in a situation
* when we cannot run concurrently all waves of the workgroup, which
* would lead to a hang.
*
* TODO: Could we spill branchstack or is there other way around?
* Blob just explodes in such case.
*/
if (v->has_barrier && (max_waves < waves_per_wg)) {
mesa_loge(
"Compute shader (%s:%s) which has workgroup barrier cannot be used "
"because it's impossible to have enough concurrent waves.",
v->shader->nir->info.name, v->shader->nir->info.label);
exit(1);
}
}
return max_waves;
}