Add a function for stream to wait for a tag

examples/cpp/19_stream_tags/.gitignore

@@ -0,0 +1,3 @@
+main
+main.o
+main_c

examples/cpp/19_stream_tags/CMakeLists.txt

@@ -0,0 +1,4 @@
+compile_cpp_example_with_modes(stream_tags main.cpp)
+
+add_custom_target(cpp_example_stream_tags_okl ALL COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_SOURCE_DIR}/powerOfPi2.okl powerOfPi2.okl)
+add_dependencies(examples_cpp_stream_tags cpp_example_stream_tags_okl)

examples/cpp/19_stream_tags/Makefile

@@ -0,0 +1,27 @@
+
+PROJ_DIR := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
+
+ifndef OCCA_DIR
+  include $(PROJ_DIR)/../../../scripts/build/Makefile
+else
+  include ${OCCA_DIR}/scripts/build/Makefile
+endif
+
+#---[ COMPILATION ]-------------------------------
+headers = $(wildcard $(incPath)/*.hpp) $(wildcard $(incPath)/*.tpp)
+sources = $(wildcard $(srcPath)/*.cpp)
+
+objects  = $(subst $(srcPath)/,$(objPath)/,$(sources:.cpp=.o))
+
+executables: ${PROJ_DIR}/main
+
+${PROJ_DIR}/main: $(objects) $(headers) ${PROJ_DIR}/main.cpp
+	$(compiler) $(compilerFlags) -o ${PROJ_DIR}/main $(flags) $(objects) ${PROJ_DIR}/main.cpp $(paths) $(linkerFlags)
+
+$(objPath)/%.o:$(srcPath)/%.cpp $(wildcard $(subst $(srcPath)/,$(incPath)/,$(<:.cpp=.hpp))) $(wildcard $(subst $(srcPath)/,$(incPath)/,$(<:.cpp=.tpp)))
+	$(compiler) $(compilerFlags) -o $@ $(flags) -c $(paths) $<
+
+clean:
+	rm -f $(objPath)/*;
+	rm -f ${PROJ_DIR}/main;
+#=================================================

examples/cpp/19_stream_tags/README.md

@@ -0,0 +1,28 @@
+# Example: Events
+
+GPU devices introduce `streams`, which potentially allow parallel queueing of instructions
+
+`Stream tags` are used to query and manage (synchronize) those streams
+
+This example shows how to setup `occa::streamTag` to manage jobs in different streams
+
+# Compiling the Example
+
+```bash
+make
+```
+
+## Usage
+
+```
+> ./main --help
+
+Usage: ./main [OPTIONS]
+
+Example showing the use of multiple non-blocking streams in a device
+
+Options:
+  -d, --device     Device properties (default: "{mode: 'CUDA', device_id: 0}")
+  -h, --help       Print usage
+  -v, --verbose    Compile kernels in verbose mode
+```

examples/cpp/19_stream_tags/main.cpp

@@ -0,0 +1,92 @@
+#include <iostream>
+
+#include <occa.hpp>
+
+//---[ Internal Tools ]-----------------
+// Note: These headers are not officially supported
+//       Please don't rely on it outside of the occa examples
+#include <occa/internal/utils/cli.hpp>
+//======================================
+
+
+occa::json parseArgs(int argc, const char **argv);
+
+int main(int argc, const char **argv) {
+  occa::json args = parseArgs(argc, argv);
+
+  occa::setDevice(occa::json::parse(args["options/device"]));
+
+  int entries = 1<<20;
+  int block = 64;
+  int group = 1;
+
+  float *a = new float[entries];
+  for (int i = 0; i < entries; i++)
+    a[i] = 0.f;
+
+  occa::memory o_a = occa::malloc<float>(entries);
+  o_a.copyFrom(a);
+
+  occa::json kernelProps({
+    {"defines/block", block},
+    {"defines/group", group},
+    {"serial/include_std", true},
+  });
+  occa::kernel powerOfPi2 = occa::buildKernel("powerOfPi2.okl",
+                                             "powerOfPi2",
+                                             kernelProps);
+  occa::json streamProps({
+    {"nonblocking", true},
+  });
+  occa::stream stream_a = occa::createStream(streamProps);
+  occa::stream stream_b = occa::createStream(streamProps);
+
+  occa::setStream(stream_a);
+  powerOfPi2(o_a, entries);
+  occa::streamTag tag_a = occa::tagStream();
+
+  // set stream_b to wait for the job(s) to be finished in stream_a
+  occa::streamWait(stream_b, tag_a);
+
+  occa::setStream(stream_b);
+  powerOfPi2(o_a, entries);
+  occa::streamTag tag_b = occa::tagStream();
+
+  // set the device to wait for stream_b to finish
+  occa::waitFor(tag_b);
+
+  o_a.copyTo(a);
+
+  const float tol = 1e-3;
+  for (auto i = 0; i < entries; i++) {
+    if (fabs(a[i] - 3.14159) > tol) {
+      std::cerr << "Invalid output value: " << a[i] << " in " << i << std::endl;
+      return -1;
+    }
+  }
+  return 0;
+}
+
+
+occa::json parseArgs(int argc, const char **argv) {
+  occa::cli::parser parser;
+  parser
+    .withDescription(
+      "Example showing the use of multiple device streams"
+    )
+    .addOption(
+      occa::cli::option('d', "device",
+                        "Device properties (default: \"{mode: 'CUDA', device_id: 0}\")")
+      .withArg()
+      .withDefaultValue("{mode: 'CUDA', device_id: 0}")
+    )
+    .addOption(
+      occa::cli::option('v', "verbose",
+                        "Compile kernels in verbose mode")
+    );
+
+  occa::json args = parser.parseArgs(argc, argv);
+  occa::settings()["kernel/verbose"] = args["options/verbose"];
+
+  return args;
+}

examples/cpp/19_stream_tags/powerOfPi2.okl

@@ -0,0 +1,10 @@
+@kernel void powerOfPi2(float* x,
+                        int entries) {
+  for (int g = 0; g < group; g++; @outer) {
+    for (int i = 0; i < block; ++i; @inner) {
+      for (int j=i+g*block; j < entries; j+=block*group) {
+        x[j] = pow(3.14159f,x[j]);
+      }
+    }
+  }
+}

examples/cpp/CMakeLists.txt

@@ -14,6 +14,7 @@ add_subdirectory(14_cuda_interop)
 add_subdirectory(17_memory_pool)
 
 add_subdirectory(18_nonblocking_streams)
+add_subdirectory(19_stream_tags)
 add_subdirectory(20_native_dpcpp_kernel)
 add_subdirectory(30_device_function)
 

include/occa/c/base.h

@@ -35,6 +35,8 @@ occaStreamTag occaTagStream();
 
 void occaWaitForTag(occaStreamTag tag);
 
+void occaStreamWaitForTag(occaStream stream, occaStreamTag tag);
+
 double occaTimeBetweenTags(occaStreamTag startTag,
                            occaStreamTag endTag);
 

include/occa/core/base.hpp

@@ -42,6 +42,7 @@ namespace occa {
   stream createStream(const occa::json &props = occa::json());
   stream getStream();
   void setStream(stream s);
+  void streamWait(stream s, streamTag tag);
 
   streamTag tagStream();
 

include/occa/core/stream.hpp

@@ -12,6 +12,7 @@
 namespace occa {
   class modeStream_t; class stream;
   class modeDevice_t; class device;
+  class streamTag;
 
   /**
    * @startDoc{stream}
@@ -148,6 +149,17 @@ namespace occa {
      */
     void finish();
 
+     /**
+     * @startDoc{waitFor}
+     *
+     * Description:
+     *   Waits for any operations submitted before a given streamg tag recording
+     *   to complete where the stream tag may be created on a different stream.
+     *
+     * @endDoc
+     */
+    void waitFor(occa::streamTag tag);
+
     /**
      * @startDoc{unwrap}
      * 

src/c/base.cpp

@@ -75,6 +75,10 @@
   occa::waitFor(occa::c::streamTag(tag));
 }
 
+void occaStreamWaitForTag(occaStream stream, occaStreamTag tag) {
+  occa::streamWait(occa::c::stream(stream), occa::c::streamTag(tag));
+}
+
 double occaTimeBetweenTags(occaStreamTag startTag,
                            occaStreamTag endTag) {
   return occa::timeBetween(occa::c::streamTag(startTag),

src/core/base.cpp

@@ -94,6 +94,10 @@
     return getDevice().tagStream();
   }
 
+  void streamWait(stream s, streamTag tag) {
+    s.waitFor(tag);
+  }
+
   memoryPool createMemoryPool(const occa::json &props) {
     return getDevice().createMemoryPool(props);
   }

src/core/stream.cpp

@@ -2,6 +2,7 @@
 #include <occa/core/device.hpp>
 #include <occa/internal/core/device.hpp>
 #include <occa/internal/core/stream.hpp>
+#include <occa/internal/core/streamTag.hpp>
 
 namespace occa {
   stream::stream() :
@@ -102,6 +103,10 @@
     if(modeStream) modeStream->finish();
   }
 
+  void stream::waitFor(occa::streamTag tag) {
+    if(modeStream) modeStream->waitFor(tag);
+  }
+
   void* stream::unwrap() {
     OCCA_ERROR(
       "stream::unwrap: stream is uninitialized or has been free'd",

src/occa/internal/api/metal/commandQueue.hpp

@@ -34,6 +34,7 @@ namespace occa {
         void freeLastCommandBuffer();
 
         event_t createEvent() const;
+        void waitForEvent(const event_t &event);
 
         void clearCommandBuffer(void *commandBufferObj);
         void setLastCommandBuffer(void *commandBufferObj);

src/occa/internal/api/metal/commandQueue.mm

@@ -77,6 +77,16 @@
                        lastCommandBufferObj);
       }
 
+      void commandQueue_t::waitForEvent(const event_t &event) {
+        if (lastCommandBufferObj) {
+          id<MTLEvent> metalEvent = (__bridge id<MTLEvent>) event.eventObj;
+          id<MTLCommandBuffer> metalCommandBuffer = (
+            (__bridge id<MTLCommandBuffer>) lastCommandBufferObj
+          );
+          [metalCommandBuffer encodeWaitForEvent:metalEvent value:event.signalValue];
+        }
+      }
+
       void commandQueue_t::clearCommandBuffer(void *commandBufferObj) {
         if (commandBufferObj == lastCommandBufferObj) {
           freeLastCommandBuffer();

src/occa/internal/api/metal/event.hpp

@@ -13,6 +13,7 @@ namespace occa {
         int eventId;
         void *commandBufferObj;
         double eventTime;
+        int signalValue;
 
         event_t();
 

src/occa/internal/api/metal/event.mm

@@ -25,10 +25,17 @@
         eventObj(eventObj_),
         eventId(eventId_),
         commandBufferObj(commandBufferObj_),
-        eventTime(0) {
+        eventTime(0),
+        signalValue(1) {
           // If there are no active command buffers, use the current time
           if (!commandBufferObj) {
             eventTime = occa::sys::currentTime();
+          } else {
+            id<MTLEvent> metalEvent = (__bridge id<MTLEvent>) eventObj;
+            id<MTLCommandBuffer> metalCommandBuffer = (
+              (__bridge id<MTLCommandBuffer>) commandBufferObj
+            );
+            [metalCommandBuffer encodeSignalEvent:metalEvent value:signalValue];
           }
         }
 
@@ -37,14 +44,16 @@
         eventId(other.eventId),
         eventObj(other.eventObj),
         commandBufferObj(other.commandBufferObj),
-        eventTime(other.eventTime) {}
+        eventTime(other.eventTime),
+        signalValue(other.signalValue) {}
 
         event_t& event_t::operator = (const event_t &other) {
         commandQueue = other.commandQueue;
         eventId = other.eventId;
         eventObj = other.eventObj;
         commandBufferObj = other.commandBufferObj;
         eventTime = other.eventTime;
+        signalValue = other.signalValue;
         return *this;
       }
 

src/occa/internal/api/metal/polyfill.cpp

@@ -73,6 +73,7 @@
       event_t commandQueue_t::createEvent() const {
         return event_t();
       }
+      void commandQueue_t::waitForEvent(const event_t &event) {}
 
       void commandQueue_t::clearCommandBuffer(void *commandBufferObj) {}
       void commandQueue_t::setLastCommandBuffer(void *commandBufferObj) {}

src/occa/internal/core/stream.hpp

@@ -25,6 +25,7 @@ namespace occa {
 
     //---[ Virtual Methods ]------------
     virtual void finish() = 0;
+    virtual void waitFor(streamTag tag) = 0;
 
     virtual void* unwrap() = 0;
     //==================================

src/occa/internal/modes/cuda/polyfill.hpp

@@ -275,6 +275,10 @@ namespace occa {
   inline CUresult cuStreamSynchronize(CUstream hStream) {
     return OCCA_CUDA_IS_NOT_ENABLED;
   }
+
+  inline CUresult cuStreamWaitEvent(CUstream hStream, CUevent hEvent, unsigned int  Flags) {
+    return OCCA_CUDA_IS_NOT_ENABLED;
+  }
 }
 
 #endif

src/occa/internal/modes/cuda/stream.cpp

@@ -1,4 +1,5 @@
 #include <occa/internal/modes/cuda/stream.hpp>
+#include <occa/internal/modes/cuda/streamTag.hpp>
 #include <occa/internal/modes/cuda/utils.hpp>
 
 namespace occa {
@@ -24,6 +25,14 @@ namespace occa {
                       cuStreamSynchronize(cuStream));
     }
 
+    void stream::waitFor(occa::streamTag tag) {
+      occa::cuda::streamTag *cuTag = (
+        dynamic_cast<occa::cuda::streamTag*>(tag.getModeStreamTag())
+      );
+      OCCA_CUDA_ERROR("Stream: waitFor",
+                      cuStreamWaitEvent(cuStream, cuTag->cuEvent, 0));
+    }
+
     void* stream::unwrap() {
       return static_cast<void*>(&cuStream);
     }

src/occa/internal/modes/cuda/stream.hpp

@@ -21,6 +21,7 @@ namespace occa {
 
       virtual ~stream();
       void finish() override;
+      void waitFor(occa::streamTag tag) override;
 
       void* unwrap() override;
     };

src/occa/internal/modes/dpcpp/polyfill.hpp

@@ -295,6 +295,7 @@ class queue {
   }
 
   sycl::event ext_oneapi_submit_barrier()  { return sycl::event();}
+  sycl::event ext_oneapi_submit_barrier( const std::vector<sycl::event> &waitList ) { return sycl::event(); }
 };
 
 inline void* malloc_device(size_t num_bytes,