#12961: Allow CQ reader and worker thread to be on different cores

tt_metal/impl/device/device.cpp

@@ -28,8 +28,8 @@ namespace tt {
 namespace tt_metal {
 
 Device::Device(
-    chip_id_t device_id, const uint8_t num_hw_cqs, size_t l1_small_size, size_t trace_region_size, const std::vector<uint32_t> &l1_bank_remap, bool minimal, uint32_t worker_core) :
-    id_(device_id), worker_thread_core(worker_core), work_executor(worker_core, device_id) {
+    chip_id_t device_id, const uint8_t num_hw_cqs, size_t l1_small_size, size_t trace_region_size, const std::vector<uint32_t> &l1_bank_remap, bool minimal, uint32_t worker_core, uint32_t completion_queue_reader_core) :
+    id_(device_id), worker_thread_core(worker_core), completion_queue_reader_core(completion_queue_reader_core), work_executor(worker_core, device_id) {
     ZoneScoped;
     tunnel_device_dispatch_workers_ = {};
     this->initialize(num_hw_cqs, l1_small_size, trace_region_size, l1_bank_remap, minimal);

tt_metal/impl/device/device.hpp

@@ -73,7 +73,8 @@ class Device {
         std::size_t trace_region_size,
         const std::vector<uint32_t> &l1_bank_remap = {},
         bool minimal = false,
-        uint32_t worker_core = 0);
+        uint32_t worker_core = 0,
+        uint32_t completion_queue_reader_core = 0);
 
     ~Device();
 
@@ -291,6 +292,7 @@ class Device {
     // all tasks scheduled on this device
     WorkExecutor work_executor;
     uint32_t worker_thread_core;
+    uint32_t completion_queue_reader_core;
     std::unique_ptr<SystemMemoryManager> sysmem_manager_;
     LaunchMessageRingBufferState worker_launch_message_buffer_state;
     uint8_t num_hw_cqs_;

tt_metal/impl/device/device_pool.cpp

@@ -33,55 +33,86 @@ std::unordered_map<int, std::vector<uint32_t>> get_cpu_cores_per_numa_node(std::
     return cpu_cores_per_numa_node;
 }
 
-int get_cpu_core_for_device_worker_thread(
+std::pair<int, int> get_cpu_core_for_device_worker_thread(
     int mmio_controlled_device_id,
     const std::unordered_map<int, std::vector<uint32_t>>& cpu_cores_per_numa_node,
-    std::unordered_set<uint32_t>& free_cores) {
-    int core_assigned_to_device = 0;
-    if (numa_available() != -1) {
-        // Get NUMA node that the current device is mapped to through UMD
-        int numa_node_for_device = tt::Cluster::instance().get_numa_node_for_device(mmio_controlled_device_id);
-        if (cpu_cores_per_numa_node.find(numa_node_for_device) != cpu_cores_per_numa_node.end()) {
-            // NUMA node reported by UMD exists on host. Choose a core on this numa-node using round robin policy
-            int num_cores_in_numa_node = cpu_cores_per_numa_node.at(numa_node_for_device).size();
-            core_assigned_to_device =
-                cpu_cores_per_numa_node.at(numa_node_for_device).at(mmio_controlled_device_id % num_cores_in_numa_node);
+    std::unordered_set<uint32_t>& free_cores,
+    uint32_t num_devices,
+    bool use_separate_procs) {
+
+    int core_assigned_to_device_worker_thread = 0;
+    int core_assigned_to_device_completion_queue_reader = 0;
+    uint32_t num_online_processors = sysconf(_SC_NPROCESSORS_ONLN);
+    // Get NUMA node that the current device is mapped to through UMD
+    int numa_node_for_device = tt::Cluster::instance().get_numa_node_for_device(mmio_controlled_device_id);
+
+    if (numa_available() != -1 and cpu_cores_per_numa_node.find(numa_node_for_device) != cpu_cores_per_numa_node.end()) {
+        // NUMA node reported by UMD exists on host. Choose a core on this numa-node using round robin policy
+        int num_cores_in_numa_node = cpu_cores_per_numa_node.at(numa_node_for_device).size();
+        core_assigned_to_device_worker_thread =
+            cpu_cores_per_numa_node.at(numa_node_for_device).at(mmio_controlled_device_id % num_cores_in_numa_node);
+        if (use_separate_procs) {
+            core_assigned_to_device_completion_queue_reader =
+                cpu_cores_per_numa_node.at(numa_node_for_device).at((mmio_controlled_device_id + num_devices) % num_cores_in_numa_node);
         } else {
-            // NUMA node reported by UMD does not exist on host. Use round-robin binding policy for this worker thread.
-            log_warning(
-                tt::LogMetal,
-                "NUMA node {} for device {} does not exist on host.",
-                numa_node_for_device,
-                mmio_controlled_device_id);
-            core_assigned_to_device = mmio_controlled_device_id % sysconf(_SC_NPROCESSORS_ONLN);
+            core_assigned_to_device_completion_queue_reader = core_assigned_to_device_worker_thread;
         }
     } else {
-        // System does not use NUMA. Use-round robin binding strategy.
-        core_assigned_to_device = mmio_controlled_device_id % sysconf(_SC_NPROCESSORS_ONLN);
+        // NUMA node reported by UMD does not exist on host. Use round-robin binding policy for this worker thread.
+        log_warning(
+            tt::LogMetal,
+            "NUMA node {} for device {} does not exist on host or NUMA is not available.",
+            numa_node_for_device,
+            mmio_controlled_device_id);
+        core_assigned_to_device_worker_thread = mmio_controlled_device_id % num_online_processors;
+        if (use_separate_procs) {
+            core_assigned_to_device_completion_queue_reader = (mmio_controlled_device_id + num_devices) % num_online_processors;
+        } else {
+            core_assigned_to_device_completion_queue_reader = core_assigned_to_device_worker_thread;
+        }
+    }
+
+    free_cores.erase(core_assigned_to_device_worker_thread);
+    if (core_assigned_to_device_completion_queue_reader != core_assigned_to_device_worker_thread) {
+        free_cores.erase(core_assigned_to_device_completion_queue_reader);
     }
-    free_cores.erase(core_assigned_to_device);
-    return core_assigned_to_device;
+    return std::make_pair(core_assigned_to_device_worker_thread, core_assigned_to_device_completion_queue_reader);
 }
 
 std::unordered_map<uint32_t, uint32_t> get_device_id_to_core_map(
     const std::vector<chip_id_t>& device_ids,
     std::unordered_set<uint32_t>& free_cores,
-    bool use_numa_node_based_thread_binding) {
-    std::unordered_map<uint32_t, uint32_t> device_to_core_map = {};
+    bool use_numa_node_based_thread_binding,
+    const uint8_t num_hw_cqs,
+    std::unordered_map<uint32_t, uint32_t>& completion_queue_reader_to_cpu_core_map) {
+    uint32_t num_online_processors = sysconf(_SC_NPROCESSORS_ONLN);
+    constexpr uint32_t max_num_procs_per_device = 2;
+    // When using multiple command queues, assign separate CPU cores to worker and completion queue reader threads,
+    // if enough processors exist on host. Atleast one core is given to the main thread.
+    bool separate_procs_for_worker_and_reader = (num_hw_cqs > 1) && (max_num_procs_per_device * device_ids.size() <= num_online_processors - 1);
+    std::unordered_map<uint32_t, uint32_t> worker_thread_to_cpu_core_map = {};
     if (use_numa_node_based_thread_binding) {
         auto cpu_cores_per_numa_node = device_cpu_allocator::get_cpu_cores_per_numa_node(free_cores);
         for (const auto& device_id : device_ids) {
-            device_to_core_map.insert(
-                {device_id,
-                 device_cpu_allocator::get_cpu_core_for_device_worker_thread(
-                     device_id, cpu_cores_per_numa_node, free_cores)});
+            auto [worker_thread_core, completion_queue_reader_core] = device_cpu_allocator::get_cpu_core_for_device_worker_thread(
+                                                                    device_id, cpu_cores_per_numa_node, free_cores, device_ids.size(), separate_procs_for_worker_and_reader);
+            worker_thread_to_cpu_core_map.insert({device_id, worker_thread_core});
+            completion_queue_reader_to_cpu_core_map.insert({device_id, completion_queue_reader_core});
         }
     } else {
+        // Round Robin CPU assignment for worker and completion queue reader threads
         for (const auto& device_id : device_ids) {
-            device_to_core_map.insert({device_id, device_id % sysconf(_SC_NPROCESSORS_ONLN)});
+            uint32_t worker_thread_proc = device_id % num_online_processors;
+            worker_thread_to_cpu_core_map.insert({device_id, worker_thread_proc});
+            if (separate_procs_for_worker_and_reader) {
+                uint32_t completion_queue_reader_proc = (device_id + device_ids.size()) % num_online_processors;
+                completion_queue_reader_to_cpu_core_map.insert({device_id, completion_queue_reader_proc});
+            } else {
+                completion_queue_reader_to_cpu_core_map.insert({device_id, worker_thread_proc});
+            }
         }
     }
-    return device_to_core_map;
+    return worker_thread_to_cpu_core_map;
 }
 
 void bind_current_thread_to_free_cores(const std::unordered_set<uint32_t>& free_cores) {
@@ -225,9 +256,10 @@ void DevicePool::activate_device(chip_id_t id) {
     }
     if (this->devices[id] == nullptr) {
         log_debug(tt::LogMetal, "DevicePool new device {}", id);
-        int core_assigned_to_device = this->device_to_core_map.at(id);
+        int worker_core_thread_core = this->worker_thread_to_cpu_core_map.at(id);
+        int completion_queue_reader_core = this->completion_queue_reader_to_cpu_core_map.at(id);
         auto dev =
-            new Device(id, this->num_hw_cqs, this->l1_small_size, this->trace_region_size, this->l1_bank_remap, false, core_assigned_to_device);
+            new Device(id, this->num_hw_cqs, this->l1_small_size, this->trace_region_size, this->l1_bank_remap, false, worker_core_thread_core, completion_queue_reader_core);
         dev->update_dispatch_cores_for_multi_cq_eth_dispatch();
         if (!this->firmware_built_keys.contains(dev->build_key())) {
             dev->build_firmware();
@@ -364,8 +396,8 @@ DevicePool::DevicePool(
         all_device_ids.emplace_back((chip_id_t)i);
     }
     std::unordered_set<uint32_t> free_cores = {};
-    this->device_to_core_map =
-        device_cpu_allocator::get_device_id_to_core_map(all_device_ids, free_cores, use_numa_node_based_thread_binding);
+    this->worker_thread_to_cpu_core_map =
+        device_cpu_allocator::get_device_id_to_core_map(all_device_ids, free_cores, use_numa_node_based_thread_binding, num_hw_cqs, this->completion_queue_reader_to_cpu_core_map);
     if (use_numa_node_based_thread_binding) {
         // Bind main thread to cores not being used by workers
         device_cpu_allocator::bind_current_thread_to_free_cores(free_cores);

tt_metal/impl/device/device_pool.hpp

@@ -63,8 +63,8 @@ class DevicePool {
     std::unordered_set<uint32_t> firmware_built_keys;
 
     // Determine which CPU cores the worker threads need to be placed on for each device
-    std::unordered_map<uint32_t, uint32_t> device_to_core_map;
-
+    std::unordered_map<uint32_t, uint32_t> worker_thread_to_cpu_core_map;
+    std::unordered_map<uint32_t, uint32_t> completion_queue_reader_to_cpu_core_map;
     void init_firmware_on_active_devices() const;
     void init_profiler_devices() const;
     void activate_device(chip_id_t id);

tt_metal/impl/dispatch/command_queue.cpp

@@ -1828,7 +1828,7 @@ HWCommandQueue::HWCommandQueue(Device* device, uint32_t id, NOC noc_index) :
     std::thread completion_queue_thread = std::thread(&HWCommandQueue::read_completion_queue, this);
     this->completion_queue_thread = std::move(completion_queue_thread);
     // Set the affinity of the completion queue reader.
-    set_device_thread_affinity(this->completion_queue_thread, device->worker_thread_core);
+    set_device_thread_affinity(this->completion_queue_thread, device->completion_queue_reader_core);
     this->expected_num_workers_completed = 0;
 }