Substring Graal performance

gistfile1.txt

==================== C2 ====================
openjdk version "25.0.2" 2026-01-20 LTS
OpenJDK Runtime Environment Corretto-25.0.2.10.1 (build 25.0.2+10-LTS)
OpenJDK 64-Bit Server VM Corretto-25.0.2.10.1 (build 25.0.2+10-LTS, mixed mode, sharing)
Java version: 25.0.2
String size: 10000
Substring length: 20
Iterations: 50000000
Total time: 756.349 ms
ns/op: 15.13

==================== GRAAL CE JIT ====================
openjdk version "25.0.1" 2025-10-21
OpenJDK Runtime Environment GraalVM CE 25.1.0-dev+8.1 (build 25.0.1+8-jvmci-25.1-b14)
OpenJDK 64-Bit Server VM GraalVM CE 25.1.0-dev+8.1 (build 25.0.1+8-jvmci-25.1-b14, mixed mode, sharing)
Java version: 25.0.1
String size: 10000
Substring length: 20
Iterations: 50000000
Total time: 596.560 ms
ns/op: 11.93

==================== GRAAL CE NI (run) ====================
Java version: 25.0.1
String size: 10000
Substring length: 20
Iterations: 50000000
Total time: 1090.902 ms
ns/op: 21.82

==================== GRAAL ORACLE JIT ====================
java version "25.0.2" 2026-01-20 LTS
Java(TM) SE Runtime Environment Oracle GraalVM 25.0.2+10.1 (build 25.0.2+10-LTS-jvmci-b01)
Java HotSpot(TM) 64-Bit Server VM Oracle GraalVM 25.0.2+10.1 (build 25.0.2+10-LTS-jvmci-b01, mixed mode, sharing)
Java version: 25.0.2
String size: 10000
Substring length: 20
Iterations: 50000000
Total time: 299.411 ms
ns/op: 5.99

==================== GRAAL Oracle NI (no PGO, run) ====================
Java version: 25.0.2
String size: 10000
Substring length: 20
Iterations: 50000000
Total time: 303.111 ms
ns/op: 6.06


----------------------------------------------------------------------
public class SubstringBenchmark {
    static final int STRING_LEN    = 10_000;
    static final int SUBSTRING_LEN = 20;
    static final int STEADY_ITERS  = 50_000_000;
    static final int WARMUP_ITERS  = 10_000_000;

    static volatile int blackhole;

    public static void main(String[] args) {
        String s = createString(STRING_LEN);

        System.out.println("Java version: " + System.getProperty("java.version"));
        System.out.println("String size: " + STRING_LEN);
        System.out.println("Substring length: " + SUBSTRING_LEN);
        System.out.println("Iterations: " + STEADY_ITERS);

        // Warmup
        for (int i = 0; i < WARMUP_ITERS; i++) {
            blackhole ^= s.substring(i % (STRING_LEN - SUBSTRING_LEN),
                                     i % (STRING_LEN - SUBSTRING_LEN) + SUBSTRING_LEN)
                            .length();
        }

        // Benchmark
        long start = System.nanoTime();

        for (int i = 0; i < STEADY_ITERS; i++) {
            int from = i % (STRING_LEN - SUBSTRING_LEN);
            String sub = s.substring(from, from + SUBSTRING_LEN);
            blackhole ^= sub.length();
        }

        long end = System.nanoTime();

        long elapsedNs = end - start;
        double nsPerOp = (double) elapsedNs / STEADY_ITERS;

        System.out.printf("Total time: %.3f ms%n", elapsedNs / 1_000_000.0);
        System.out.printf("ns/op: %.2f%n", nsPerOp);
    }

    private static String createString(int size) {
        char[] chars = new char[size];
        for (int i = 0; i < size; i++) {
            chars[i] = (char) ('a' + (i % 26));
        }
        return new String(chars);
    }
}

----------------------------------------------------------------------
echo "==================== C2 ===================="
. /wf/c2.sh
java -version
java -XX:+UnlockExperimentalVMOptions -XX:+Use${gc}GC -Xms4g -Xmx4g ${bench}

echo "==================== GRAAL CE JIT ===================="
. /wf/graal_25_ce.sh
java -version
java -XX:+UnlockExperimentalVMOptions -XX:+Use${gc}GC -Xms4g -Xmx4g ${bench}

echo "==================== GRAAL CE NI (compile) ===================="
native-image --gc=$2 -O3 ${bench} -o ${bench}

echo "==================== GRAAL CE NI (run) ===================="
taskset -c 0 ./${bench}

echo "==================== GRAAL ORACLE JIT ===================="
. /wf/graal_25_oracle.sh
java -version
java -XX:+UnlockExperimentalVMOptions -XX:+Use${gc}GC -Xms4g -Xmx4g ${bench}

echo "==================== GRAAL Oracle NI (compile) ===================="
native-image --gc=$2 -O3 ${bench} -o ${bench}

echo "==================== GRAAL Oracle NI (run) ===================="
taskset -c 0 ./${bench}


----------------------------------------------------------------------
@ARM-BENCH ~  $ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=24.04
DISTRIB_CODENAME=noble
DISTRIB_DESCRIPTION="Ubuntu 24.04.2 LTS"

----------------------------------------------------------------------
instance-type:                     c7g.metal
ami-id:                            ami-0c4e709339fa8521a