Add info how to enable Graal JIT with Oracle JDK

Author: olyagpl

compiler/java-stream-benchmark/README.md

@@ -1,7 +1,6 @@
 # Java Stream Benchmark
 
-This repository contains the code for a simple Java Stream benchmark designed to run on a JDK.
-
+This repository contains the code for a simple Java Stream benchmark designed to run on the [GraalVM JDK](http://graalvm.org) and the [Oracle JDK](https://www.oracle.com/java/technologies/downloads/).
 ## Preparation
 
 1. Download and install the GraalVM JDK using [SDKMAN!](https://sdkman.io/). For other installation options, visit the [Downloads page](https://www.graalvm.org/downloads/).
@@ -29,23 +28,36 @@ Now you can run this benchmark with whatever `java` you have on your machine and
 Note that the results you see can be influenced by the hardware you are running this benchmark on, the CPU load, and other factors.
 Interpret them responsibly.
 
-## Run the Benchmark
+### GraalVM JDK with Graal JIT
+
+Run the benchmark with the default GraalVM JIT compiler by executing the _target/benchmarks.jar_ file:
+```bash
+java -jar target/benchmarks.jar
+```
+
+### GraalVM JDK with Graal JIT Deactivated
 
-1. Run the benchmark on the **GraalVM JDK with the default JIT compiler (Graal)** by executing the _target/benchmarks.jar_ file:
+Now deactivate the Graal compiler and run the benchmark on the same JVM (GraalVM):
+```bash
+java -XX:-UseJVMCICompiler -jar target/benchmarks.jar
+```
+This way, the Graal JIT compiler is not be used as the JVMCI compiler and the JVM uses its default one (C2).
+
+### Oracle JDK with Graal JIT
+
+Note that starting with Oracle JDK 23, the **Oracle GraalVM JIT compiler (Graal JIT) is now included among the JITs available as part of the Oracle JDK**.
+Read more in [this blog post](https://blogs.oracle.com/java/post/including-the-graal-jit-in-oracle-jdk-23).
+
+1. Switch the JVM from GraalVM (Oracle GraalVM or Community Edition) to Oracle JDK 23 or higher. You can quickly do that with using [SDKMAN!](https://sdkman.io/):
     ```bash
-    java -jar target/benchmarks.jar
+    sdk install java 23.0.1-oracle 
     ```
 
-2. Now **deactivate the Graal compiler** using the `-XX:-UseJVMCICompiler` option and run the benchmark on the same JVM (GraalVM):
+2. Run this benchmark with the Graal JIT compiler enabled. For that, pass the `-XX:+UseGraalJIT` option to `java`:
     ```bash
-    java -XX:-UseJVMCICompiler -jar target/benchmarks.jar
+    java -XX:+UnlockExperimentalVMOptions -XX:+UseGraalJIT -jar target/benchmarks.jar
     ```
-    This way, the Graal JIT compiler is not be used as the JVMCI compiler and the JVM uses its default one.
-
-## Learn More
 
-Learn more about the Graal JIT compiler from [its official documentation](https://www.graalvm.org/reference-manual/java/compiler/).
+> To switch between JVMs in the same terminal window (without affecting the global setting), use the `sdk` tool. For example, to switch back to Oracle GraalVM for JDK 23, run: `sdk use java 23.0.1-graal`.
 
-Note that starting with Oracle JDK 23, the **Oracle GraalVM JIT compiler (Graal JIT) is now included among the JITs available as part of the Oracle JDK**. 
-To run a Java application on Oracle JDK with the Graal JIT compiler, pass the `-XX:+UseGraalJIT` option to `java`. 
-Read more in [this blog post](https://blogs.oracle.com/java/post/including-the-graal-jit-in-oracle-jdk-23).
+Learn more about the Graal JIT compiler from [its official documentation](https://www.graalvm.org/reference-manual/java/compiler/).