Enforce the kernel to run cache shrinker via /proc/sys/vm/drop_caches.

Delete sample input file and add two simple test cases for purge status.

4 files changed, 52 insertions, 60 deletions

diff --git a/ashmemtest-expanded/ashmemtest-expanded.l b/ashmemtest-expanded/ashmemtest-expanded.l
index 074a948..f13c7a5 100644
--- a/ashmemtest-expanded/ashmemtest-expanded.l
+++ b/ashmemtest-expanded/ashmemtest-expanded.l
@@ -42,7 +42,7 @@ range_t * parse_range (char *);
 void getpages (int);
 void pinpages (range_t *);
 void unpinpages (range_t *);
-void pressure (int);
+void shrink (void);
 void purgepages (void);
 void fatal (int, const char *, ...);
 
@@ -56,13 +56,13 @@ pin[ \t]+[0-9]+[ \t]+[0-9]+	{ pinpages (parse_range (yytext + 3)); }
 
 unpin[ \t]+[0-9]+[ \t]+[0-9]+	{ unpinpages (parse_range (yytext + 5)); }
 
-alloc[ \t]+[0-9]+		{ pressure (parse_number (yytext + 5)); }
+shrink				{ shrink (); }
 
 purge				{ purgepages (); }
 
 [ \t\n]+			/* spaces */
 
-[ \t]*#.+			/* comment starts from '#' */
+[ \t]*#.*			/* comment starts from '#' */
 
 .				{ fprintf (stderr, "Unrecognized input '%s' at line %d\n",
 					   yytext, yylineno);
@@ -145,6 +145,7 @@ void
 pinpages (range_t *range)
 {
   struct ashmem_pin pin;
+  int ret;
 
   if (ashmemfd == -1)
     fatal (0, "pages not allocated (use getpages X first)");
@@ -154,9 +155,10 @@ pinpages (range_t *range)
       /* Normal order, pin all at once. */
       pin.offset = range->beg * pagesize;
       pin.len = (range->end - range->beg) * pagesize;
-      if (ioctl (ashmemfd, ASHMEM_PIN, &pin) < 0)
+      ret = ioctl (ashmemfd, ASHMEM_PIN, &pin);
+      if (ret < 0)
 	fatal (errno, "can't pin %d..%d", range->beg, range->end);
-      printf ("-> pin %d..%d OK\n", range->beg, range->end);
+      printf ("-> pin %d..%d OK ret %d\n", range->beg, range->end, ret);
     }
   else
     {
@@ -167,7 +169,8 @@ pinpages (range_t *range)
 	{
 	  pin.offset = pgno * pagesize;
 	  pin.len = pagesize;
-	  if (ioctl (ashmemfd, ASHMEM_PIN, &pin) < 0)
+	  ret = ioctl (ashmemfd, ASHMEM_PIN, &pin);
+	  if (ret < 0)
 	    fatal (errno, "can't pin page %d", pgno);
 	}
       printf ("-> pin backward %d..%d OK\n", range->beg, range->end);
@@ -178,6 +181,7 @@ void
 unpinpages (range_t *range)
 {
   struct ashmem_pin pin;
+  int ret;
 
   if (ashmemfd == -1)
     fatal (0, "pages not allocated (use getpages X first)");
@@ -187,9 +191,10 @@ unpinpages (range_t *range)
       /* Normal order, unpin all at once. */
       pin.offset = range->beg * pagesize;
       pin.len = (range->end - range->beg) * pagesize;
-      if (ioctl (ashmemfd, ASHMEM_UNPIN, &pin) < 0)
+      ret = ioctl (ashmemfd, ASHMEM_UNPIN, &pin);
+      if (ret < 0)
 	fatal (errno, "can't unpin %d..%d", range->beg, range->end);
-      printf ("-> unpin %d..%d OK\n", range->beg, range->end);
+      printf ("-> unpin %d..%d OK ret %d\n", range->beg, range->end, ret);
     }
   else
     {
@@ -200,45 +205,29 @@ unpinpages (range_t *range)
 	{
 	  pin.offset = pgno * pagesize;
 	  pin.len = pagesize;
-	  if (ioctl (ashmemfd, ASHMEM_UNPIN, &pin) < 0)
+	  ret = ioctl (ashmemfd, ASHMEM_UNPIN, &pin);
+	  if (ret < 0)
 	    fatal (errno, "can't unpin page %d", pgno);
 	}
       printf ("-> unpin backward %d..%d OK\n", range->beg, range->end);
     }
 }
 
-/* Percentage is of physical RAM */
+/* Enforce the kernel to run cache shrinker */
 
 void
-pressure (int percentage)
+shrink (void)
 {
-  struct sysinfo si;
-  int mbytes;
-  char *mem;
-
-  if (sysinfo (&si) < 0)
-    fatal (0, "can't obtain system information");
-  mbytes = (si.totalram >> 20) * percentage / 100;
-  switch (fork ())
-    {
-    case 0: /* child */
-      mem = (char *) malloc (mbytes << 20);
-      if (!mem)
-	fatal (0, "can't allocate %d MBytes", mbytes);
-      else
-	{
-	  printf ("-> child allocates %d MBytes\n", mbytes);
-	  memset (mem, 0, mbytes << 20);
-	  /* let's wait for OOM killer */
-	  pause ();
-	}
-      /* NOTREACHED */
-      break;
-    case -1: /* error */
-      fatal (errno, "can't fork");
-    default: /* parent */
-      break;
-    }
+  int fd;
+  char cmd[2];
+
+  fd = open ("/proc/sys/vm/drop_caches", O_WRONLY);
+  if (fd < 0)
+    fatal (errno, "can't open /proc/sys/vm/drop_caches (is /proc mounted?)");
+  cmd[0] = '3';
+  cmd[1] = '\n';
+  if (write (fd, cmd, sizeof cmd) != sizeof cmd)
+    fatal (errno, "can't write to /proc/sys/vm/drop_caches");
 }
 
 void
diff --git a/ashmemtest-expanded/example.txt b/ashmemtest-expanded/example.txt
deleted file mode 100644
index 73ae92c..0000000
--- a/ashmemtest-expanded/example.txt
+++ /dev/null
@@ -1,22 +0,0 @@
-# Example input for ashmemtest-expanded test program.
-
-# Get 1000 pages
-getpages 1000
-
-# Unpin pages 100..200
-unpin 100 200
-
-# Unpin pages 400..300 (in that order, e.g. backward)
-unpin 400 300
-
-# Allocate huge chunk (90% of physical RAM)
-alloc 90
-
-# Pin 100..200 back
-pin 100 200
-
-# Pin 300..400 back (in normal order)
-pin 300 400
-
-# Purge all
-purge
diff --git a/ashmemtest-expanded/test0.txt b/ashmemtest-expanded/test0.txt
new file mode 100644
index 0000000..83c39a9
--- /dev/null
+++ b/ashmemtest-expanded/test0.txt
@@ -0,0 +1,12 @@
+# Simple test to make sure that the pages aren't purged initially.
+# Expected output is:
+#
+# -> got 1000 pages
+# -> unpin 0..500 OK ret 0
+# -> pin 0..500 OK ret 0
+#
+# Here the last pin operation should return 0 (e.g. ASHMEM_NOT_PURGED).
+
+getpages 1000
+unpin 0 500
+pin 0 500
diff --git a/ashmemtest-expanded/test1.txt b/ashmemtest-expanded/test1.txt
new file mode 100644
index 0000000..6ecd6df
--- /dev/null
+++ b/ashmemtest-expanded/test1.txt
@@ -0,0 +1,13 @@
+# Simple test to call cache shrinker.  Expected output is:
+#
+# -> got 1000 pages
+# -> unpin 0..500 OK ret 0
+# -> pin 0..500 OK ret 1
+#
+# Here the call to kernel cache shrinker should give 1
+# (e.g. ASHMEM_WAS_PURGED) for the last pin operation.
+
+getpages 1000
+unpin 0 500
+shrink
+pin 0 500