membomb: add mmap variant

Author: rfjakob

contrib/membomb/.gitignore

@@ -1,3 +1,6 @@
 /membomb
 /membomb.subthread
 /membomb.mmap
+/keep_active
+/membomb.mmap_anon
+/membomb.mmap_file

contrib/membomb/Makefile

@@ -1,21 +1,27 @@
 CFLAGS += -Wall -Wextra -g -fstack-protector-all -std=gnu99
 
 .PHONY: all
-all: membomb membomb.subthread membomb.mmap
+all: membomb membomb.subthread membomb.mmap_anon membomb.mmap_file keep_active
 
 membomb : $(wildcard *.c *.h) Makefile
 	$(CC) $(CFLAGS) -o $@ eat_all_memory.c membomb.c
 
 membomb.subthread: $(wildcard *.c *.h) Makefile
 	$(CC) $(CFLAGS) -lpthread -o $@ eat_all_memory.c membomb.subthread.c
 
-membomb.mmap: $(wildcard *.c *.h) Makefile
-	$(CC) $(CFLAGS) -lpthread -o $@ eat_all_memory.c membomb.mmap.c
+membomb.mmap_anon: $(wildcard *.c *.h) Makefile
+	$(CC) $(CFLAGS) -lpthread -o $@ eat_all_memory.c membomb.mmap_anon.c
+
+membomb.mmap_file: $(wildcard *.c *.h) Makefile
+	$(CC) $(CFLAGS) -lpthread -o $@ eat_all_memory.c membomb.mmap_file.c
+
+keep_active: $(wildcard *.c *.h) Makefile
+	$(CC) $(CFLAGS) -lpthread -o $@ keep_active.c
 
 .PHONY: format
 format:
 	clang-format --style=file -i *.c
 
 .PHONY: clean
 clean:
-	rm -f membomb membomb.subthread membomb.mmap
+	rm -f membomb membomb.subthread membomb.mmap_anon membomb.mmap_file keep_active

contrib/membomb/eat_all_memory.c

@@ -1,3 +1,5 @@
+#include <errno.h>
+#include <fcntl.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -7,8 +9,6 @@
 
 #include "eat_all_memory.h"
 
-#define NUM_PAGES 10
-
 static void handle_sigterm(int sig)
 {
     printf("blocking SIGTERM %d\n", sig);
@@ -17,7 +17,11 @@ static void handle_sigterm(int sig)
 void eat_all_memory(eat_how_enum eat_how)
 {
     long page_size = sysconf(_SC_PAGESIZE);
-    long bs = page_size * NUM_PAGES;
+    long num_pages = 10;
+    if (eat_how == EAT_MMAP_FILE) {
+        num_pages = 10000;
+    }
+    long bs = page_size * num_pages;
     long cnt = 0, last_sum = 0;
     struct timeval tv1;
     signal(SIGTERM, handle_sigterm);
@@ -39,16 +43,42 @@ void eat_all_memory(eat_how_enum eat_how)
                 continue;
             }
             break;
+        case EAT_MMAP_FILE:
+            char tmp_path[] = "/var/tmp/membomb.mmap_file.XXXXXX";
+            int fd = mkstemp(tmp_path);
+            if (fd == -1) {
+                perror("mkstemp failed");
+                sleep(1);
+                continue;
+            }
+            int ret = unlink(tmp_path);
+            if (ret) {
+                perror("unlink failed");
+            }
+            if (ret) {
+                errno = ret;
+                perror("ftruncate failed");
+                sleep(1);
+                continue;
+            }
+            p = mmap(NULL, bs, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+            if (p == MAP_FAILED) {
+                perror("mmap failed");
+                sleep(1);
+                continue;
+            }
+            break;
         default:
             fprintf(stderr, "BUG: unknown eat_how=%d\n", eat_how);
             exit(1);
         }
-        for (int i = 0; i < NUM_PAGES; i++) {
+        for (int i = 0; i < num_pages; i++) {
             // Write to each page so the kernel really has to allocate it.
             p[i * page_size] = 0xab;
         }
         cnt++;
-        if (cnt % 1000 == 0) {
+        const int cnt_per_100mb = 100 * 1024 * 1024 / bs;
+        if (cnt % cnt_per_100mb == 0) {
             long sum = bs * cnt / 1024 / 1024;
             struct timeval tv2;
             gettimeofday(&tv2, NULL);

contrib/membomb/eat_all_memory.h

@@ -1,6 +1,7 @@
 typedef enum {
     EAT_MALLOC,
     EAT_MMAP_ANON,
+    EAT_MMAP_FILE,
 } eat_how_enum;
 
 void eat_all_memory(eat_how_enum eat_how);

contrib/membomb/keep_active.c

@@ -0,0 +1,59 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+int main()
+{
+    const long gigabyte = 1024 * 1024 * 1024;
+    const long size = 10 * gigabyte;
+    char tmp_path[] = "/var/tmp/keep_active.XXXXXX";
+    int fd = mkstemp(tmp_path);
+    if (fd == -1) {
+        perror("mkstemp failed");
+        exit(1);
+    }
+    int ret = unlink(tmp_path);
+    if (ret) {
+        perror("unlink failed");
+        exit(1);
+    }
+    ret = posix_fallocate(fd, 0, size);
+    if (ret) {
+        errno = ret;
+        perror("posix_fallocate failed");
+        exit(1);
+    }
+    fsync(fd);
+
+    printf("Allocated %ld GiB\n", size / gigabyte);
+    printf("Spinning on file reads...\n");
+    struct timeval tv1;
+    gettimeofday(&tv1, NULL);
+    while (1) {
+        long increment = sysconf(_SC_PAGESIZE);
+        char buf[1];
+        for (long off = 0; off < size; off += increment) {
+            ret = pread(fd, buf, sizeof(buf), off);
+            if (ret <= 0) {
+                perror("pread");
+                exit(1);
+            }
+        }
+        // Print stats
+        struct timeval tv2;
+        gettimeofday(&tv2, NULL);
+        long delta = tv2.tv_sec - tv1.tv_sec;
+        // Convert to microseconds
+        delta *= 1000000;
+        // Add microsecond delta
+        delta = delta + tv2.tv_usec - tv1.tv_usec;
+        // Byte-per-Microsecond = MB/s
+        long mbps = size / delta;
+        printf("%4ld MiB (%4ld MiB/s)\n", size / 1024 / 1024, mbps);
+        gettimeofday(&tv1, NULL);
+    }
+}

contrib/membomb/membomb.mmap.c contrib/membomb/membomb.mmap_anon.ccontrib/membomb/membomb.mmap.c renamed to contrib/membomb/membomb.mmap_anon.c

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: MIT
+
+/* Use up all memory that we can get, as fast as we can.
+ * As progress information, prints how much memory we already
+ * have.
+ *
+ * This file is part of the earlyoom project: https://github.com/rfjakob/earlyoom
+ */
+
+#include <stdio.h>
+
+#include "eat_all_memory.h"
+
+int main()
+{
+    printf("Using mmap on normal file\n");
+    eat_all_memory(EAT_MMAP_FILE);
+}