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Adding indirect command buffer emulation for Metal. (#17849)
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Until we switch to using MTLIndirectCommandBuffer any reusable command
buffers or ones with indirect bindings will need to be recorded into
deferred command buffers and replayed upon submission.
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@benvanik
benvanik committed Jul 10, 2024
1 parent 9ac1015 commit e000353
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Showing 2 changed files with 86 additions and 15 deletions.
1 change: 1 addition & 0 deletions runtime/src/iree/hal/drivers/metal/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@ iree_cc_library(
iree::base::internal::flatcc::parsing
iree::hal
iree::hal::drivers::metal::builtin
iree::hal::utils::deferred_command_buffer
iree::hal::utils::file_transfer
iree::hal::utils::memory_file
iree::hal::utils::resource_set
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100 changes: 85 additions & 15 deletions runtime/src/iree/hal/drivers/metal/metal_device.m
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include "iree/hal/drivers/metal/pipeline_layout.h"
#include "iree/hal/drivers/metal/shared_event.h"
#include "iree/hal/drivers/metal/staging_buffer.h"
#include "iree/hal/utils/deferred_command_buffer.h"
#include "iree/hal/utils/file_transfer.h"
#include "iree/hal/utils/memory_file.h"
#include "iree/hal/utils/resource_set.h"
Expand Down Expand Up @@ -247,12 +248,17 @@ static iree_status_t iree_hal_metal_device_create_command_buffer(
iree_host_size_t binding_capacity, iree_hal_command_buffer_t** out_command_buffer) {
iree_hal_metal_device_t* device = iree_hal_metal_device_cast(base_device);

if (!iree_all_bits_set(mode, IREE_HAL_COMMAND_BUFFER_MODE_ONE_SHOT)) {
return iree_make_status(IREE_STATUS_UNIMPLEMENTED,
"multi-shot command buffer not yet supported");
} else if (binding_capacity > 0) {
return iree_make_status(IREE_STATUS_UNIMPLEMENTED,
"indirect command buffers not yet supported");
// Native Metal command buffers are not reusable so we emulate by recording into our own reusable
// instance. This will be replayed against a Metal command buffer upon submission.
//
// TODO(indirect-cmd): natively support indirect command buffers in Metal via
// MTLIndirectCommandBuffer. We could switch to exclusively using that for all modes to keep the
// number of code paths down. MTLIndirectCommandBuffer is both reusable and has what we require
// for argument buffer updates to pass in binding tables.
if (!iree_all_bits_set(mode, IREE_HAL_COMMAND_BUFFER_MODE_ONE_SHOT) || binding_capacity > 0) {
return iree_hal_deferred_command_buffer_create(
device->device_allocator, mode, command_categories, binding_capacity, &device->block_pool,
device->host_allocator, out_command_buffer);
}

return iree_hal_metal_direct_command_buffer_create(
Expand Down Expand Up @@ -390,6 +396,38 @@ static iree_status_t iree_hal_metal_device_queue_write(
return loop_status;
}

static iree_status_t iree_hal_metal_replay_command_buffer(
iree_hal_metal_device_t* device, iree_hal_command_buffer_t* deferred_command_buffer,
iree_hal_buffer_binding_table_t binding_table,
iree_hal_command_buffer_t** out_direct_command_buffer) {
IREE_TRACE_ZONE_BEGIN(z0);

// Create the transient command buffer. Note that it is one-shot and has no indirect bindings as
// we will be replaying it once with all the bindings resolved.
iree_hal_command_buffer_t* direct_command_buffer = NULL;
IREE_RETURN_AND_END_ZONE_IF_ERROR(
z0, iree_hal_metal_direct_command_buffer_create(
(iree_hal_device_t*)device, IREE_HAL_COMMAND_BUFFER_MODE_ONE_SHOT,
iree_hal_command_buffer_allowed_categories(deferred_command_buffer),
/*binding_capacity=*/0, device->command_buffer_resource_reference_mode, device->queue,
&device->block_pool, &device->staging_buffer, device->builtin_executable,
device->host_allocator, &direct_command_buffer));

// Attempt to replay all commands against the transient command buffer. Note that this will fail
// if any binding does not meet the requirements - having succeeded when recording initially is
// not a guarantee that this will succeed.
iree_status_t status = iree_hal_deferred_command_buffer_apply(
deferred_command_buffer, direct_command_buffer, binding_table);

if (iree_status_is_ok(status)) {
*out_direct_command_buffer = direct_command_buffer;
} else {
iree_hal_command_buffer_release(direct_command_buffer);
}
IREE_TRACE_ZONE_END(z0);
return status;
}

static iree_status_t iree_hal_metal_device_queue_execute(
iree_hal_device_t* base_device, iree_hal_queue_affinity_t queue_affinity,
const iree_hal_semaphore_list_t wait_semaphore_list,
Expand All @@ -403,20 +441,46 @@ static iree_status_t iree_hal_metal_device_queue_execute(
IREE_RETURN_AND_END_ZONE_IF_ERROR(
z0, iree_hal_resource_set_allocate(&device->block_pool, &resource_set));

iree_status_t status =
iree_hal_resource_set_insert(resource_set, command_buffer_count, command_buffers);

// Put the full semaphore list into a resource set, which retains them--we will need to access
// them until the command buffer completes.
if (iree_status_is_ok(status)) {
status = iree_hal_resource_set_insert(resource_set, wait_semaphore_list.count,
wait_semaphore_list.semaphores);
}
iree_status_t status = iree_hal_resource_set_insert(resource_set, wait_semaphore_list.count,
wait_semaphore_list.semaphores);
if (iree_status_is_ok(status)) {
status = iree_hal_resource_set_insert(resource_set, signal_semaphore_list.count,
signal_semaphore_list.semaphores);
}

// Translate any deferred command buffers into real Metal command buffers.
// We do this prior to beginning execution so that if we fail we don't leave the system in an
// inconsistent state.
iree_hal_command_buffer_t** direct_command_buffers = (iree_hal_command_buffer_t**)iree_alloca(
command_buffer_count * sizeof(iree_hal_command_buffer_t*));
if (iree_status_is_ok(status)) {
for (iree_host_size_t i = 0; i < command_buffer_count; ++i) {
iree_hal_command_buffer_t* command_buffer = command_buffers[i];
iree_hal_command_buffer_t* direct_command_buffer = NULL;
if (iree_hal_deferred_command_buffer_isa(command_buffer)) {
// Create a temporary command buffer and replay the deferred command buffer with the
// binding table provided. Note that any resources used will be retained by the command
// buffer so we only need to retain the command buffer itself instead of the binding
// tables provided.
iree_hal_buffer_binding_table_t binding_table =
binding_tables ? binding_tables[i] : iree_hal_buffer_binding_table_empty();
@autoreleasepool {
status = iree_hal_metal_replay_command_buffer(device, command_buffer, binding_table,
&direct_command_buffer);
}
} else {
// Retain the command buffer until the submission has completed.
direct_command_buffer = command_buffer;
}
if (!iree_status_is_ok(status)) break;
status = iree_hal_resource_set_insert(resource_set, 1, &direct_command_buffer);
if (!iree_status_is_ok(status)) break;
direct_command_buffers[i] = direct_command_buffer;
}
}

if (iree_status_is_ok(status)) {
@autoreleasepool {
// First create a new command buffer and encode wait commands for all wait semaphores.
Expand All @@ -436,8 +500,14 @@ static iree_status_t iree_hal_metal_device_queue_execute(
// up with semaphore signaling.
id<MTLCommandBuffer> signal_command_buffer = nil;
for (iree_host_size_t i = 0; i < command_buffer_count; ++i) {
iree_hal_command_buffer_t* command_buffer = command_buffers[i];
id<MTLCommandBuffer> handle = iree_hal_metal_direct_command_buffer_handle(command_buffer);
// NOTE: translation happens above such that we always know these are direct command
// buffers.
//
// TODO(indirect-cmd): support indirect command buffers and switch here, or only use
// indirect command buffers and assume that instead.
iree_hal_command_buffer_t* direct_command_buffer = direct_command_buffers[i];
id<MTLCommandBuffer> handle =
iree_hal_metal_direct_command_buffer_handle(direct_command_buffer);
if (i + 1 != command_buffer_count) [handle commit];
signal_command_buffer = handle;
}
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