Revert "[SYCL] Clear extensions functions cache upon context release (#5282)" (#5433)

This reverts commit 2eed402.

Revert is due massive performance regression introduced.
Employing of spin-lock and/or pre-initialization didn't help reduce performance impact.

Author: sergei

sycl/plugins/opencl/ext_functions.inc

@@ -25,8 +25,6 @@
 #include <iostream>
 #include <limits>
 #include <map>
-#include <memory>
-#include <mutex>
 #include <sstream>
 #include <string>
 #include <vector>
@@ -73,93 +71,19 @@ CONSTFIX char clGetDeviceFunctionPointerName[] =
 
 #undef CONSTFIX
 
-typedef CL_API_ENTRY cl_int(CL_API_CALL *clGetDeviceFunctionPointer_fn)(
-    cl_device_id device, cl_program program, const char *FuncName,
-    cl_ulong *ret_ptr);
-
-typedef CL_API_ENTRY cl_int(CL_API_CALL *clSetProgramSpecializationConstant_fn)(
-    cl_program program, cl_uint spec_id, size_t spec_size,
-    const void *spec_value);
-
-struct ExtFuncsPerContextT;
-
-namespace detail {
-template <const char *FuncName, typename FuncT>
-std::pair<FuncT &, bool &> get(ExtFuncsPerContextT &);
-} // namespace detail
-
-struct ExtFuncsPerContextT {
-#define _EXT_FUNCTION_INTEL(t_pfx)                                             \
-  t_pfx##INTEL_fn t_pfx##Func = nullptr;                                       \
-  bool t_pfx##Initialized = false;
-
-#define _EXT_FUNCTION(t_pfx)                                                   \
-  t_pfx##_fn t_pfx##Func = nullptr;                                            \
-  bool t_pfx##Initialized = false;
-
-#include "ext_functions.inc"
-
-#undef _EXT_FUNCTION
-#undef _EXT_FUNCTION_INTEL
-
-  std::mutex Mtx;
-
-  template <const char *FuncName, typename FuncT>
-  std::pair<FuncT &, bool &> get() {
-    return detail::get<FuncName, FuncT>(*this);
-  }
-};
-
-namespace detail {
-
-#define _EXT_FUNCTION_COMMON(t_pfx, t_pfx_suff)                                \
-  template <>                                                                  \
-  std::pair<t_pfx_suff##_fn &, bool &> get<t_pfx##Name, t_pfx_suff##_fn>(      \
-      ExtFuncsPerContextT & Funcs) {                                           \
-    using FPtrT = t_pfx_suff##_fn;                                             \
-    std::pair<FPtrT &, bool &> Ret{Funcs.t_pfx##Func,                          \
-                                   Funcs.t_pfx##Initialized};                  \
-    return Ret;                                                                \
-  }
-#define _EXT_FUNCTION_INTEL(t_pfx) _EXT_FUNCTION_COMMON(t_pfx, t_pfx##INTEL)
-#define _EXT_FUNCTION(t_pfx) _EXT_FUNCTION_COMMON(t_pfx, t_pfx)
-
-#include "ext_functions.inc"
-
-#undef _EXT_FUNCTION
-#undef _EXT_FUNCTION_INTEL
-#undef _EXT_FUNCTION_COMMON
-} // namespace detail
-
-struct ExtFuncsCachesT {
-  std::map<pi_context, ExtFuncsPerContextT> Caches;
-  std::mutex Mtx;
-};
-
-ExtFuncsCachesT *ExtFuncsCaches = nullptr;
-
 // USM helper function to get an extension function pointer
 template <const char *FuncName, typename T>
 static pi_result getExtFuncFromContext(pi_context context, T *fptr) {
   // TODO
   // Potentially redo caching as PI interface changes.
-  ExtFuncsPerContextT *PerContext = nullptr;
-  {
-    assert(ExtFuncsCaches);
-    std::lock_guard<std::mutex> Lock{ExtFuncsCaches->Mtx};
-
-    PerContext = &ExtFuncsCaches->Caches[context];
-  }
-
-  std::lock_guard<std::mutex> Lock{PerContext->Mtx};
-  std::pair<T &, bool &> FuncInitialized = PerContext->get<FuncName, T>();
+  thread_local static std::map<pi_context, T> FuncPtrs;
 
   // if cached, return cached FuncPtr
-  if (FuncInitialized.second) {
+  if (auto F = FuncPtrs[context]) {
     // if cached that extension is not available return nullptr and
     // PI_INVALID_VALUE
-    *fptr = FuncInitialized.first;
-    return *fptr ? PI_SUCCESS : PI_INVALID_VALUE;
+    *fptr = F;
+    return F ? PI_SUCCESS : PI_INVALID_VALUE;
   }
 
   cl_uint deviceCount;
@@ -191,17 +115,14 @@ static pi_result getExtFuncFromContext(pi_context context, T *fptr) {
   T FuncPtr =
       (T)clGetExtensionFunctionAddressForPlatform(curPlatform, FuncName);
 
-  // We're about to store the cached value. Mark this cache entry initialized.
-  FuncInitialized.second = true;
-
   if (!FuncPtr) {
     // Cache that the extension is not available
-    FuncInitialized.first = nullptr;
+    FuncPtrs[context] = nullptr;
     return PI_INVALID_VALUE;
   }
 
-  FuncInitialized.first = FuncPtr;
   *fptr = FuncPtr;
+  FuncPtrs[context] = FuncPtr;
 
   return cast<pi_result>(ret_err);
 }
@@ -641,6 +562,9 @@ static bool is_in_separated_string(const std::string &str, char delimiter,
   return false;
 }
 
+typedef CL_API_ENTRY cl_int(CL_API_CALL *clGetDeviceFunctionPointer_fn)(
+    cl_device_id device, cl_program program, const char *FuncName,
+    cl_ulong *ret_ptr);
 pi_result piextGetDeviceFunctionPointer(pi_device device, pi_program program,
                                         const char *func_name,
                                         pi_uint64 *function_pointer_ret) {
@@ -1381,6 +1305,10 @@ pi_result piKernelSetExecInfo(pi_kernel kernel, pi_kernel_exec_info param_name,
   }
 }
 
+typedef CL_API_ENTRY cl_int(CL_API_CALL *clSetProgramSpecializationConstant_fn)(
+    cl_program program, cl_uint spec_id, size_t spec_size,
+    const void *spec_value);
+
 pi_result piextProgramSetSpecializationConstant(pi_program prog,
                                                 pi_uint32 spec_id,
                                                 size_t spec_size,
@@ -1456,21 +1384,9 @@ pi_result piextKernelGetNativeHandle(pi_kernel kernel,
 // pi_level_zero.cpp for reference) Currently this is just a NOOP.
 pi_result piTearDown(void *PluginParameter) {
   (void)PluginParameter;
-  delete ExtFuncsCaches;
-  ExtFuncsCaches = nullptr;
   return PI_SUCCESS;
 }
 
-pi_result piContextRelease(pi_context Context) {
-  {
-    std::lock_guard<std::mutex> Lock{ExtFuncsCaches->Mtx};
-
-    ExtFuncsCaches->Caches.erase(Context);
-  }
-
-  return cast<pi_result>(clReleaseContext(cast<cl_context>(Context)));
-}
-
 pi_result piPluginInit(pi_plugin *PluginInit) {
   int CompareVersions = strcmp(PluginInit->PiVersion, SupportedVersion);
   if (CompareVersions < 0) {
@@ -1482,8 +1398,6 @@ pi_result piPluginInit(pi_plugin *PluginInit) {
   // PI interface supports higher version or the same version.
   strncpy(PluginInit->PluginVersion, SupportedVersion, 4);
 
-  ExtFuncsCaches = new ExtFuncsCachesT;
-
 #define _PI_CL(pi_api, ocl_api)                                                \
   (PluginInit->PiFunctionTable).pi_api = (decltype(&::pi_api))(&ocl_api);
 
@@ -1507,7 +1421,7 @@ pi_result piPluginInit(pi_plugin *PluginInit) {
   _PI_CL(piContextCreate, piContextCreate)
   _PI_CL(piContextGetInfo, clGetContextInfo)
   _PI_CL(piContextRetain, clRetainContext)
-  _PI_CL(piContextRelease, piContextRelease)
+  _PI_CL(piContextRelease, clReleaseContext)
   _PI_CL(piextContextGetNativeHandle, piextContextGetNativeHandle)
   _PI_CL(piextContextCreateWithNativeHandle, piextContextCreateWithNativeHandle)
   // Queue

sycl/plugins/opencl/pi_opencl.cpp

@@ -8,7 +8,6 @@
 # UNSUPPORTED: libcxx
 
 piContextCreate
-piContextRelease
 piDeviceGetInfo
 piDevicesGet
 piEnqueueMemBufferMap