From ebb93550f5e0f2b634eefe3a52e923732f4a7327 Mon Sep 17 00:00:00 2001
From: John S Peterson <jpeterson57@gmail.com>
Date: Tue, 28 May 2024 23:50:19 +0300
Subject: [PATCH] WIP: save the memory allocation progress in the case the
 process is terminated on Out Of Memory and print it on the next run

anything can happen when testing the memory limit including losing the entire shell. this will save progress to disk while trying to write to large amounts of memory
---
 src/stress.c | 39 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/stress.c b/src/stress.c
index a02c53e..d498466 100644
--- a/src/stress.c
+++ b/src/stress.c
@@ -79,7 +79,7 @@ void worker_init(void);
 /* Prototypes for worker functions.  */
 int hogcpu (void);
 int hogio (void);
-int hogvm (long long bytes, long long stride, long long hang, int keep);
+int hogvm (long long bytes, long long stride, long long hang, int keep, int spin);
 int hoghdd (long long bytes);
 
 int
@@ -87,6 +87,8 @@ main (int argc, char **argv)
 {
     int i, pid, children = 0, retval = 0;
     long starttime, stoptime, runtime, forks;
+    long long progress;
+    FILE *f;
 
     /* Variables that indicate which options have been selected.  */
     int do_dryrun = 0;
@@ -98,6 +100,7 @@ main (int argc, char **argv)
     long long do_vm_bytes = 256 * 1024 * 1024;
     long long do_vm_stride = 4096;
     long long do_vm_hang = -1;
+    int do_vm_spin = 1;
     int do_vm_keep = 0;
     long long do_hdd = 0;
     long long do_hdd_bytes = 1024 * 1024 * 1024;
@@ -226,6 +229,10 @@ main (int argc, char **argv)
         {
             do_vm_keep = 1;
         }
+        else if (strcmp (arg, "--vm-no-spin") == 0)
+        {
+            do_vm_spin = 0;
+        }
         else if (strcmp (arg, "--hdd") == 0 || strcmp (arg, "-d") == 0)
         {
             assert_arg ("--hdd");
@@ -259,6 +266,13 @@ main (int argc, char **argv)
         out (stdout, "dispatching hogs: %lli cpu, %lli io, %lli vm, %lli hdd\n",
              do_cpu, do_io, do_vm, do_hdd);
     }
+    else if (f = fopen("stress.progress", "r"))
+    {
+    	fscanf(f, "%lli", &progress);
+    	out (stdout, "Previous run was able to write %llim before termination\n", progress / 1024 / 1024);
+    	remove("stress.progress");
+        return 0;
+    }
     else
         usage (0);
 
@@ -350,7 +364,7 @@ main (int argc, char **argv)
                 usleep (backoff);
                 if (do_dryrun)
                     exit (0);
-                exit (hogvm (do_vm_bytes, do_vm_stride, do_vm_hang, do_vm_keep));
+                exit (hogvm (do_vm_bytes, do_vm_stride, do_vm_hang, do_vm_keep, do_vm_spin));
             case -1:           /* error */
                 err (stderr, "fork failed: %s\n", strerror (errno));
                 break;
@@ -495,12 +509,13 @@ hogio ()
 }
 
 int
-hogvm (long long bytes, long long stride, long long hang, int keep)
+hogvm (long long bytes, long long stride, long long hang, int keep, int spin)
 {
-    long long i;
+    long long i, j;
     char *ptr = 0;
     char c;
     int do_malloc = 1;
+    FILE *f;
 
     while (1)
     {
@@ -517,8 +532,21 @@ hogvm (long long bytes, long long stride, long long hang, int keep)
         }
 
         dbg (stdout, "touching bytes in strides of %lli bytes ...\n", stride);
-        for (i = 0; i < bytes; i += stride)
+        f = fopen("stress.progress", "w");
+        for (i = 0; i < bytes; i += stride, j += stride)
+        {
             ptr[i] = 'Z';           /* Ensure that COW happens.  */
+              
+            // save progress and flush regularly  if everything  trashed by the system
+            rewind(f);
+            fprintf(f, "%lli", i);
+            if (j > 10 * 1024 * 1024) {
+                fflush(f);
+                j = 0;
+            }
+         }
+         
+        if (spin == 0) return 0;
 
         if (hang == 0)
         {
@@ -768,6 +796,7 @@ usage (int status)
         "     --vm-bytes B   malloc B bytes per vm worker (default is 256MB)\n"
         "     --vm-stride B  touch a byte every B bytes (default is 4096)\n"
         "     --vm-hang N    sleep N secs before free (default none, 0 is inf)\n"
+        "     --vm-no-spin   do not spin on malloc\n"
         "     --vm-keep      redirty memory instead of freeing and reallocating\n"
         " -d, --hdd N        spawn N workers spinning on write()/unlink()\n"
         "     --hdd-bytes B  write B bytes per hdd worker (default is 1GB)\n\n"