Userland: Add test program for stressing memory allocation

Userland/allocate.cpp

@@ -0,0 +1,98 @@
+#include <AK/AKString.h>
+#include <LibCore/CElapsedTimer.h>
+#include <stdio.h>
+#include <unistd.h>
+
+void usage(void)
+{
+    printf("usage: allocate [number [unit (B/KB/MB)]]\n");
+    exit(1);
+}
+
+enum Unit { Bytes, KiloBytes, MegaBytes };
+
+int main(int argc, char** argv)
+{
+    unsigned count = 50;
+    Unit unit = MegaBytes;
+
+    if (argc >= 2) {
+        bool ok;
+        count = String(argv[1]).to_uint(ok);
+        if (!ok) {
+            usage();
+        }
+    }
+
+    if (argc >= 3) {
+        if (strcmp(argv[2], "B") == 0)
+            unit = Bytes;
+        else if (strcmp(argv[2], "KB") == 0)
+            unit = KiloBytes;
+        else if (strcmp(argv[2], "MB") == 0)
+            unit = MegaBytes;
+        else
+            usage();
+    }
+
+    switch (unit) {
+    case Bytes:
+        break;
+    case KiloBytes:
+        count *= 1024;
+        break;
+    case MegaBytes:
+        count *= 1024 * 1024;
+        break;
+    }
+
+    CElapsedTimer timer;
+
+    printf("allocating memory (%d bytes)...\n", count);
+    timer.start();
+    char* ptr = (char*)malloc(count);
+    if (!ptr) {
+        printf("failed.\n");
+        return 1;
+    }
+    printf("done in %dms\n", timer.elapsed());
+
+    auto pages = count / 4096;
+    auto step = pages / 10;
+
+    CElapsedTimer timer2;
+
+    printf("writing one byte to each page of allocated memory...\n");
+    timer.start();
+    timer2.start();
+    for (int i = 0; i < pages; ++i) {
+        ptr[i * 4096] = 1;
+
+        if (i != 0 && (i % step) == 0) {
+            auto ms = timer2.elapsed();
+            if (ms == 0)
+                ms = 1;
+
+            auto bps = double(step * 4096) / (double(ms) / 1000);
+
+            printf("step took %dms (%fMB/s)\n", ms, bps / 1024 / 1024);
+
+            timer2.start();
+        }
+    }
+    printf("done in %dms\n", timer.elapsed());
+
+    printf("sleeping for ten seconds...\n");
+    for (int i = 0; i < 10; i++) {
+        printf("%d\n", i);
+        sleep(1);
+    }
+    printf("done.\n");
+
+    printf("freeing memory...\n");
+    timer.start();
+    free(ptr);
+    printf("done in %dms\n", timer.elapsed());
+
+    return 0;
+}