Adding README for benchmark

Signed-off-by: Sayed Bilal Bari <[email protected]>

core/src/main/scala/org/apache/spark/rapids/tool/benchmarks/README.md

@@ -0,0 +1,32 @@
+# Benchmarking Tools
+
+This package contains the relevant classes to write and run benchmarks for `RAPIDS TOOLS` for Apache Spark.
+
+## Writing a benchmark -
+* Extend `BenchmarkBase` and override the `runBenchmarkSuite` function
+* Write logically similar benchmarks inside the `runBenchmark` which will add a header to the output with the name provided.
+* Now for each case to be tested, use the Benchmark class `addCase` to write various cases of the same Benchmark.
+* Call the run function to run the benchmark
+* Refer included example benchmark - `SingleThreadedQualToolBenchmark` for implementation details
+
+## Running the benchmark -
+Use the java command to run the created benchmark class with the following supported params -
+* `-i` : total number of iterations to run to calculate average metrics
+* `-w` : total number of warmup iterations to run before calculating the final metrics ( warmup is relevant so that final results are not skewed by the initial java classloading times )
+* `-o` : output directory where to store the final result file. Defaults to the directory rapids-tools-benchmark in the root directory
+* `-f` : output format of the stored result. Currently supports text. Json to be added in future iterations
+* `-a` : input arguments to pass the underlying benchmark classes
+
+#### Running the Benchmark class directly
+```shell
+java -cp $CLASSPATH \
+com.nvidia.spark.rapids.tool.benchmarks.SingleThreadedQualToolBenchmark \
+-i 3 -w 3 -a " --output-directory output eventlogs"
+```
+#### Running the Benchmark class using tools jar
+```shell
+java -cp /home/rapids-4-spark-tools_2.12-24.06.2-SNAPSHOT.jar:$SPARK_HOME/jars/* \
+org.apache.spark.rapids.tool.benchmarks.SingleThreadedQualToolBenchmark \
+-i 3 -w 3 -a "/home/eventlogs"
+```
+Include the `SPARK` jars in the classpath to benchmark `QUALIFICATION/PROFILING` tool