[SYCL] Reduce number of getenv calls (#4321)

This change avoids repeated calls to getenv when launching parallel_for kernels
to improve performance of short-running parallel_for kernels on Windows.

Signed-off-by: rdeodhar rajiv.deodhar@intel.com

Author: rdeodhar

sycl/include/CL/sycl/handler.hpp

@@ -780,33 +780,17 @@ class __SYCL_EXPORT handler {
     // Range should be at least this to make rounding worthwhile.
     size_t MinRangeX = 1024;
 
-    // Parse optional parameters of this form:
-    // MinRound:PreferredRound:MinRange
-    char *RoundParams = getenv("SYCL_PARALLEL_FOR_RANGE_ROUNDING_PARAMS");
-    if (RoundParams != nullptr) {
-      std::string Params(RoundParams);
-      size_t Pos = Params.find(':');
-      if (Pos != std::string::npos) {
-        MinFactorX = std::stoi(Params.substr(0, Pos));
-        Params.erase(0, Pos + 1);
-        Pos = Params.find(':');
-        if (Pos != std::string::npos) {
-          GoodFactorX = std::stoi(Params.substr(0, Pos));
-          Params.erase(0, Pos + 1);
-          MinRangeX = std::stoi(Params);
-        }
-      }
-    }
+    // Check if rounding parameters have been set through environment:
+    // SYCL_PARALLEL_FOR_RANGE_ROUNDING_PARAMS=MinRound:PreferredRound:MinRange
+    this->GetRangeRoundingSettings(MinFactorX, GoodFactorX, MinRangeX);
 
     // Disable the rounding-up optimizations under these conditions:
     // 1. The env var SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING is set.
-    // 2. The string SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING is in
-    //    the kernel name.
-    // 3. The kernel is provided via an interoperability method.
-    // 4. The API "this_item" is used inside the kernel.
-    // 5. The range is already a multiple of the rounding factor.
+    // 2. The kernel is provided via an interoperability method.
+    // 3. The API "this_item" is used inside the kernel.
+    // 4. The range is already a multiple of the rounding factor.
     //
-    // Cases 3 and 4 could be supported with extra effort.
+    // Cases 2 and 3 could be supported with extra effort.
     // As an optimization for the common case it is an
     // implementation choice to not support those scenarios.
     // Note that "this_item" is a free function, i.e. not tied to any
@@ -816,13 +800,11 @@ class __SYCL_EXPORT handler {
     // call-graph to make this_item calls kernel-specific but this is
     // not considered worthwhile.
 
-    // Get the kernal name to check condition 3.
+    // Get the kernel name to check condition 2.
     std::string KName = typeid(NameT *).name();
     using KI = detail::KernelInfo<KernelName>;
     bool DisableRounding =
-        (getenv("SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING") != nullptr) ||
-        (KName.find("SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING") !=
-         std::string::npos) ||
+        this->DisableRangeRounding() ||
         (KI::getName() == nullptr || KI::getName()[0] == '\0') ||
         (KI::callsThisItem());
 
@@ -837,7 +819,7 @@ class __SYCL_EXPORT handler {
       // will yield a rounded-up value for the total range.
       size_t NewValX =
           ((NumWorkItems[0] + GoodFactorX - 1) / GoodFactorX) * GoodFactorX;
-      if (getenv("SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE") != nullptr)
+      if (this->RangeRoundingTrace())
         std::cout << "parallel_for range adjusted from " << NumWorkItems[0]
                   << " to " << NewValX << std::endl;
 
@@ -2451,6 +2433,13 @@ class __SYCL_EXPORT handler {
 
   friend class ::MockHandler;
 
+  bool DisableRangeRounding();
+
+  bool RangeRoundingTrace();
+
+  void GetRangeRoundingSettings(size_t &MinFactor, size_t &GoodFactor,
+                                size_t &MinRange);
+
   template <typename WrapperT, typename TransformedArgType, int Dims,
             typename KernelType>
   auto getRangeRoundedKernelLambda(KernelType KernelFunc,

sycl/source/detail/config.def

@@ -15,6 +15,9 @@ CONFIG(SYCL_DISABLE_EXECUTION_GRAPH_CLEANUP, 1, __SYCL_DISABLE_EXECUTION_GRAPH_C
 CONFIG(SYCL_DEVICE_ALLOWLIST, 1024, __SYCL_DEVICE_ALLOWLIST)
 CONFIG(SYCL_BE, 16, __SYCL_BE)
 CONFIG(SYCL_PI_TRACE, 16, __SYCL_PI_TRACE)
+CONFIG(SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE, 16, __SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE)
+CONFIG(SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING, 16, __SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING)
+CONFIG(SYCL_PARALLEL_FOR_RANGE_ROUNDING_PARAMS, 64, __SYCL_PARALLEL_FOR_RANGE_ROUNDING_PARAMS)
 CONFIG(SYCL_DEVICELIB_NO_FALLBACK, 1, __SYCL_DEVICELIB_NO_FALLBACK)
 CONFIG(SYCL_DEVICE_FILTER, 1024, __SYCL_DEVICE_FILTER)
 CONFIG(SYCL_PROGRAM_LINK_OPTIONS, 64, __SYCL_PROGRAM_LINK_OPTIONS)

sycl/source/detail/config.hpp

@@ -176,6 +176,64 @@ template <> class SYCLConfig<SYCL_PI_TRACE> {
   }
 };
 
+template <> class SYCLConfig<SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE> {
+  using BaseT = SYCLConfigBase<SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE>;
+
+public:
+  static bool get() {
+    static const char *ValStr = BaseT::getRawValue();
+    return ValStr != nullptr;
+  }
+};
+
+template <> class SYCLConfig<SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING> {
+  using BaseT = SYCLConfigBase<SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING>;
+
+public:
+  static bool get() {
+    static const char *ValStr = BaseT::getRawValue();
+    return ValStr != nullptr;
+  }
+};
+
+template <> class SYCLConfig<SYCL_PARALLEL_FOR_RANGE_ROUNDING_PARAMS> {
+  using BaseT = SYCLConfigBase<SYCL_PARALLEL_FOR_RANGE_ROUNDING_PARAMS>;
+
+private:
+public:
+  static void GetSettings(size_t &MinFactor, size_t &GoodFactor,
+                          size_t &MinRange) {
+    static const char *RoundParams = BaseT::getRawValue();
+    if (RoundParams == nullptr)
+      return;
+
+    static bool ProcessedFactors = false;
+    static size_t MF;
+    static size_t GF;
+    static size_t MR;
+    if (!ProcessedFactors) {
+      // Parse optional parameters of this form (all values required):
+      // MinRound:PreferredRound:MinRange
+      std::string Params(RoundParams);
+      size_t Pos = Params.find(':');
+      if (Pos != std::string::npos) {
+        MF = std::stoi(Params.substr(0, Pos));
+        Params.erase(0, Pos + 1);
+        Pos = Params.find(':');
+        if (Pos != std::string::npos) {
+          GF = std::stoi(Params.substr(0, Pos));
+          Params.erase(0, Pos + 1);
+          MR = std::stoi(Params);
+        }
+      }
+      ProcessedFactors = true;
+    }
+    MinFactor = MF;
+    GoodFactor = GF;
+    MinRange = MR;
+  }
+};
+
 // Array is used by SYCL_DEVICE_FILTER and SYCL_DEVICE_ALLOWLIST
 const std::array<std::pair<std::string, info::device_type>, 5> &
 getSyclDeviceTypeMap();

sycl/source/handler.cpp

@@ -15,6 +15,7 @@
 #include <CL/sycl/handler.hpp>
 #include <CL/sycl/info/info_desc.hpp>
 #include <CL/sycl/stream.hpp>
+#include <detail/config.hpp>
 #include <detail/global_handler.hpp>
 #include <detail/kernel_bundle_impl.hpp>
 #include <detail/kernel_impl.hpp>
@@ -496,6 +497,21 @@ void handler::barrier(const std::vector<event> &WaitList) {
       [](const event &Event) { return detail::getSyclObjImpl(Event); });
 }
 
+using namespace sycl::detail;
+bool handler::DisableRangeRounding() {
+  return SYCLConfig<SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING>::get();
+}
+
+bool handler::RangeRoundingTrace() {
+  return SYCLConfig<SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE>::get();
+}
+
+void handler::GetRangeRoundingSettings(size_t &MinFactor, size_t &GoodFactor,
+                                       size_t &MinRange) {
+  SYCLConfig<SYCL_PARALLEL_FOR_RANGE_ROUNDING_PARAMS>::GetSettings(
+      MinFactor, GoodFactor, MinRange);
+}
+
 void handler::memcpy(void *Dest, const void *Src, size_t Count) {
   throwIfActionIsCreated();
   MSrcPtr = const_cast<void *>(Src);

sycl/test/abi/sycl_symbols_linux.dump

@@ -3899,9 +3899,12 @@ _ZN2cl4sycl7handler10mem_adviseEPKvmi
 _ZN2cl4sycl7handler10processArgEPvRKNS0_6detail19kernel_param_kind_tEimRmb
 _ZN2cl4sycl7handler10processArgEPvRKNS0_6detail19kernel_param_kind_tEimRmbb
 _ZN2cl4sycl7handler13getKernelNameB5cxx11Ev
+_ZN2cl4sycl7handler18RangeRoundingTraceEv
 _ZN2cl4sycl7handler18extractArgsAndReqsEv
+_ZN2cl4sycl7handler20DisableRangeRoundingEv
 _ZN2cl4sycl7handler20associateWithHandlerEPNS0_6detail16AccessorBaseHostENS0_6access6targetE
 _ZN2cl4sycl7handler22setHandlerKernelBundleERKSt10shared_ptrINS0_6detail18kernel_bundle_implEE
+_ZN2cl4sycl7handler24GetRangeRoundingSettingsERmS2_S2_
 _ZN2cl4sycl7handler28extractArgsAndReqsFromLambdaEPcmPKNS0_6detail19kernel_param_desc_tE
 _ZN2cl4sycl7handler28extractArgsAndReqsFromLambdaEPcmPKNS0_6detail19kernel_param_desc_tEb
 _ZN2cl4sycl7handler6memcpyEPvPKvm

sycl/test/abi/sycl_symbols_windows.dump

@@ -596,6 +596,7 @@
 ?Any@__host_std@cl@@YAHV?$vec@_J$0BA@@sycl@2@@Z
 ?Clear@exception_list@sycl@cl@@AEAAXXZ
 ?DirSep@OSUtil@detail@sycl@cl@@2QEBDEB
+?DisableRangeRounding@handler@sycl@cl@@AEAA_NXZ
 ?Dot@__host_std@cl@@YA?AVhalf@half_impl@detail@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$00@62@0@Z
 ?Dot@__host_std@cl@@YA?AVhalf@half_impl@detail@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$01@62@0@Z
 ?Dot@__host_std@cl@@YA?AVhalf@half_impl@detail@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$02@62@0@Z
@@ -747,6 +748,7 @@
 ?FUnordNotEqual@__host_std@cl@@YAHVhalf@half_impl@detail@sycl@2@0@Z
 ?GetNativeMem@interop_handler@sycl@cl@@AEBA_KPEAVAccessorImplHost@detail@23@@Z
 ?GetNativeQueue@interop_handler@sycl@cl@@AEBA_KXZ
+?GetRangeRoundingSettings@handler@sycl@cl@@AEAAXAEA_K00@Z
 ?IsFinite@__host_std@cl@@YA?AV?$vec@F$00@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$00@42@@Z
 ?IsFinite@__host_std@cl@@YA?AV?$vec@F$01@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$01@42@@Z
 ?IsFinite@__host_std@cl@@YA?AV?$vec@F$02@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$02@42@@Z
@@ -877,6 +879,7 @@
 ?PushBack@exception_list@sycl@cl@@AEAAX$$QEAVexception_ptr@std@@@Z
 ?PushBack@exception_list@sycl@cl@@AEAAXAEBVexception_ptr@std@@@Z
 ?REJECT_DEVICE_SCORE@device_selector@sycl@cl@@1HB
+?RangeRoundingTrace@handler@sycl@cl@@AEAA_NXZ
 ?SignBitSet@__host_std@cl@@YA?AV?$vec@F$00@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$00@42@@Z
 ?SignBitSet@__host_std@cl@@YA?AV?$vec@F$01@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$01@42@@Z
 ?SignBitSet@__host_std@cl@@YA?AV?$vec@F$02@sycl@2@V?$vec@Vhalf@half_impl@detail@sycl@cl@@$02@42@@Z