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Merge pull request #42981 from lyuma/command_queue_fix_3.2

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[3.2] Backport Command queue fix
This commit is contained in:
Rémi Verschelde 2020-10-22 09:55:49 +02:00 committed by GitHub
commit 438e4f1e1a
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 36 additions and 16 deletions
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18
core/command_queue_mt.cpp
View file

@ -31,6 +31,7 @@
#include "command_queue_mt.h" #include "command_queue_mt.h"
#include "core/os/os.h" #include "core/os/os.h"
#include "core/project_settings.h"
void CommandQueueMT::lock() { void CommandQueueMT::lock() {
@ -79,7 +80,7 @@ CommandQueueMT::SyncSemaphore *CommandQueueMT::_alloc_sync_sem() {
bool CommandQueueMT::dealloc_one() { bool CommandQueueMT::dealloc_one() {
tryagain: tryagain:
if (dealloc_ptr == write_ptr) { if (dealloc_ptr == (write_ptr_and_epoch >> 1)) {
// The queue is empty // The queue is empty
return false; return false;
} }
@ -103,22 +104,27 @@ tryagain:
CommandQueueMT::CommandQueueMT(bool p_sync) { CommandQueueMT::CommandQueueMT(bool p_sync) {
read_ptr = 0; read_ptr_and_epoch = 0;
write_ptr = 0; write_ptr_and_epoch = 0;
dealloc_ptr = 0; dealloc_ptr = 0;
mutex = Mutex::create(); mutex = Mutex::create();
command_mem = (uint8_t *)memalloc(COMMAND_MEM_SIZE);
command_mem_size = GLOBAL_DEF_RST("memory/limits/command_queue/multithreading_queue_size_kb", DEFAULT_COMMAND_MEM_SIZE_KB);
ProjectSettings::get_singleton()->set_custom_property_info("memory/limits/command_queue/multithreading_queue_size_kb", PropertyInfo(Variant::INT, "memory/limits/command_queue/multithreading_queue_size_kb", PROPERTY_HINT_RANGE, "1,4096,1,or_greater"));
command_mem_size *= 1024;
command_mem = (uint8_t *)memalloc(command_mem_size);
for (int i = 0; i < SYNC_SEMAPHORES; i++) { for (int i = 0; i < SYNC_SEMAPHORES; i++) {
sync_sems[i].sem = Semaphore::create(); sync_sems[i].sem = Semaphore::create();
sync_sems[i].in_use = false; sync_sems[i].in_use = false;
} }
if (p_sync) if (p_sync) {
sync = Semaphore::create(); sync = Semaphore::create();
else } else {
sync = NULL; sync = NULL;
} }
}
CommandQueueMT::~CommandQueueMT() { CommandQueueMT::~CommandQueueMT() {

34
core/command_queue_mt.h
View file

@ -311,15 +311,15 @@ class CommandQueueMT {
/***** BASE *******/ /***** BASE *******/
enum { enum {
COMMAND_MEM_SIZE_KB = 256, DEFAULT_COMMAND_MEM_SIZE_KB = 256,
COMMAND_MEM_SIZE = COMMAND_MEM_SIZE_KB * 1024,
SYNC_SEMAPHORES = 8 SYNC_SEMAPHORES = 8
}; };
uint8_t *command_mem; uint8_t *command_mem;
uint32_t read_ptr; uint32_t read_ptr_and_epoch;
uint32_t write_ptr; uint32_t write_ptr_and_epoch;
uint32_t dealloc_ptr; uint32_t dealloc_ptr;
uint32_t command_mem_size;
SyncSemaphore sync_sems[SYNC_SEMAPHORES]; SyncSemaphore sync_sems[SYNC_SEMAPHORES];
Mutex *mutex; Mutex *mutex;
Semaphore *sync; Semaphore *sync;
@ -330,7 +330,11 @@ class CommandQueueMT {
// alloc size is size+T+safeguard // alloc size is size+T+safeguard
uint32_t alloc_size = ((sizeof(T) + 8 - 1) & ~(8 - 1)) + 8; uint32_t alloc_size = ((sizeof(T) + 8 - 1) & ~(8 - 1)) + 8;
// Assert that the buffer is big enough to hold at least two messages.
ERR_FAIL_COND_V(alloc_size * 2 + sizeof(uint32_t) > command_mem_size, NULL);
tryagain: tryagain:
uint32_t write_ptr = write_ptr_and_epoch >> 1;
if (write_ptr < dealloc_ptr) { if (write_ptr < dealloc_ptr) {
// behind dealloc_ptr, check that there is room // behind dealloc_ptr, check that there is room
@ -345,7 +349,7 @@ class CommandQueueMT {
} else { } else {
// ahead of dealloc_ptr, check that there is room // ahead of dealloc_ptr, check that there is room
if ((COMMAND_MEM_SIZE - write_ptr) < alloc_size + sizeof(uint32_t)) { if ((command_mem_size - write_ptr) < alloc_size + sizeof(uint32_t)) {
// no room at the end, wrap down; // no room at the end, wrap down;
if (dealloc_ptr == 0) { // don't want write_ptr to become dealloc_ptr if (dealloc_ptr == 0) { // don't want write_ptr to become dealloc_ptr
@ -358,12 +362,17 @@ class CommandQueueMT {
} }
// if this happens, it's a bug // if this happens, it's a bug
ERR_FAIL_COND_V((COMMAND_MEM_SIZE - write_ptr) < 8, NULL); ERR_FAIL_COND_V((command_mem_size - write_ptr) < 8, NULL);
// zero means, wrap to beginning // zero means, wrap to beginning
uint32_t *p = (uint32_t *)&command_mem[write_ptr]; uint32_t *p = (uint32_t *)&command_mem[write_ptr];
*p = 0; *p = 1;
write_ptr = 0; write_ptr_and_epoch = 0 | (1 & ~write_ptr_and_epoch); // Invert epoch.
// See if we can get the thread to run and clear up some more space while we wait.
// This is required if alloc_size * 2 + 4 > COMMAND_MEM_SIZE
if (sync) {
sync->post();
}
goto tryagain; goto tryagain;
} }
} }
@ -377,6 +386,7 @@ class CommandQueueMT {
// allocate the command // allocate the command
T *cmd = memnew_placement(&command_mem[write_ptr], T); T *cmd = memnew_placement(&command_mem[write_ptr], T);
write_ptr += size; write_ptr += size;
write_ptr_and_epoch = (write_ptr << 1) | (write_ptr_and_epoch & 1);
return cmd; return cmd;
} }
@ -402,17 +412,19 @@ class CommandQueueMT {
tryagain: tryagain:
// tried to read an empty queue // tried to read an empty queue
if (read_ptr == write_ptr) { if (read_ptr_and_epoch == write_ptr_and_epoch) {
if (p_lock) unlock(); if (p_lock) unlock();
return false; return false;
} }
uint32_t read_ptr = read_ptr_and_epoch >> 1;
uint32_t size_ptr = read_ptr; uint32_t size_ptr = read_ptr;
uint32_t size = *(uint32_t *)&command_mem[read_ptr] >> 1; uint32_t size = *(uint32_t *)&command_mem[read_ptr] >> 1;
if (size == 0) { if (size == 0) {
*(uint32_t *)&command_mem[read_ptr] = 0; // clear in-use bit.
//end of ringbuffer, wrap //end of ringbuffer, wrap
read_ptr = 0; read_ptr_and_epoch = 0 | (1 & ~read_ptr_and_epoch); // Invert epoch.
goto tryagain; goto tryagain;
} }
@ -422,6 +434,8 @@ class CommandQueueMT {
read_ptr += size; read_ptr += size;
read_ptr_and_epoch = (read_ptr << 1) | (read_ptr_and_epoch & 1);
if (p_lock) unlock(); if (p_lock) unlock();
cmd->call(); cmd->call();
if (p_lock) lock(); if (p_lock) lock();