swr: [rasterizer core] refactor thread creation

Create worker pool now computes number of worker threads based on
things like topologies, etc. and creates the pool but doesn't actually
launch the threads. Instead there is a separate start thread pool
function. This allows thread resources to be constructed first before
threads start.

Signed-off-by: Tim Rowley <timothy.o.rowley@intel.com>

src/gallium/drivers/swr/rasterizer/core/api.cpp

@@ -159,7 +159,7 @@ HANDLE SwrCreateContext(
 
     pCreateInfo->contextSaveSize = sizeof(API_STATE);
 
-    WakeAllThreads(pContext);
+    StartThreadPool(pContext, &pContext->threadPool);
 
     return (HANDLE)pContext;
 }

src/gallium/drivers/swr/rasterizer/core/threads.cpp

@@ -718,11 +718,6 @@ DWORD workerThreadMain(LPVOID pData)
     //    the worker can safely increment its oldestDraw counter and move on to the next draw.
     std::unique_lock<std::mutex> lock(pContext->WaitLock, std::defer_lock);
 
-    // Suspend thread immediately. SwrCreateContext or QueueWork will wake this up again.
-    lock.lock();
-    pContext->FifosNotEmpty.wait(lock);
-    lock.unlock();
-
     auto threadHasWork = [&](uint32_t curDraw) { return curDraw != pContext->dcRing.GetHead(); };
 
     uint32_t curDrawBE = 0;
@@ -807,7 +802,11 @@ DWORD workerThreadInit(LPVOID pData)
 }
 template<> DWORD workerThreadInit<false, false>(LPVOID pData) = delete;
 
-void CreateThreadPool(SWR_CONTEXT *pContext, THREAD_POOL *pPool)
+//////////////////////////////////////////////////////////////////////////
+/// @brief Creates thread pool info but doesn't launch threads.
+/// @param pContext - pointer to context
+/// @param pPool - pointer to thread pool object.
+void CreateThreadPool(SWR_CONTEXT* pContext, THREAD_POOL* pPool)
 {
     bindThread(pContext, 0);
 
@@ -953,7 +952,6 @@ void CreateThreadPool(SWR_CONTEXT *pContext, THREAD_POOL *pPool)
             pPool->pThreadData[workerId].htId = 0;
             pPool->pThreadData[workerId].pContext = pContext;
             pPool->pThreadData[workerId].forceBindProcGroup = bForceBindProcGroup;
-            pPool->pThreads[workerId] = new std::thread(workerThreadInit<true, true>, &pPool->pThreadData[workerId]);
 
             pContext->NumBEThreads++;
             pContext->NumFEThreads++;
@@ -999,7 +997,6 @@ void CreateThreadPool(SWR_CONTEXT *pContext, THREAD_POOL *pPool)
                     pPool->pThreadData[workerId].htId = t;
                     pPool->pThreadData[workerId].pContext = pContext;
 
-                    pPool->pThreads[workerId] = new std::thread(workerThreadInit<true, true>, &pPool->pThreadData[workerId]);
                     pContext->NumBEThreads++;
                     pContext->NumFEThreads++;
 
@@ -1007,9 +1004,31 @@ void CreateThreadPool(SWR_CONTEXT *pContext, THREAD_POOL *pPool)
                 }
             }
         }
+        SWR_ASSERT(workerId == pContext->NumWorkerThreads);
+    }
+}
+
+//////////////////////////////////////////////////////////////////////////
+/// @brief Launches worker threads in thread pool.
+/// @param pContext - pointer to context
+/// @param pPool - pointer to thread pool object.
+void StartThreadPool(SWR_CONTEXT* pContext, THREAD_POOL* pPool)
+{
+    if (pContext->threadInfo.SINGLE_THREADED)
+    {
+        return;
+    }
+
+    for (uint32_t workerId = 0; workerId < pContext->NumWorkerThreads; ++workerId)
+    {
+        pPool->pThreads[workerId] = new std::thread(workerThreadInit<true, true>, &pPool->pThreadData[workerId]);
     }
 }
 
+//////////////////////////////////////////////////////////////////////////
+/// @brief Destroys thread pool.
+/// @param pContext - pointer to context
+/// @param pPool - pointer to thread pool object.
 void DestroyThreadPool(SWR_CONTEXT *pContext, THREAD_POOL *pPool)
 {
     if (!pContext->threadInfo.SINGLE_THREADED)

src/gallium/drivers/swr/rasterizer/core/threads.h

@@ -60,6 +60,7 @@ struct THREAD_POOL
 typedef std::unordered_set<uint32_t> TileSet;
 
 void CreateThreadPool(SWR_CONTEXT *pContext, THREAD_POOL *pPool);
+void StartThreadPool(SWR_CONTEXT* pContext, THREAD_POOL* pPool);
 void DestroyThreadPool(SWR_CONTEXT *pContext, THREAD_POOL *pPool);
 
 // Expose FE and BE worker functions to the API thread if single threaded