[Watchdog-devel] [PATCH] Add allocatable memory test

[Eric B M. <em...@ak...>]

Monitoring of free memory as reported in meminfo doesn't actually give
us a picture of what is allocatable.  A better metric for this case is
to try and allocate an amount.  This test attempts to mmap the specified
number of pages and fault them in.

Signed-off-by: Eric B Munson <em...@ak...>
---
 include/extern.h |    2 ++
 src/configfile.c |    5 +++++
 src/memory.c     |   25 +++++++++++++++++++++++++
 src/watchdog.c   |    3 +++
 4 files changed, 35 insertions(+)

diff --git a/include/extern.h b/include/extern.h
index 04c0ccc..77bcb11 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -65,6 +65,7 @@ extern int maxload1;
 extern int maxload5;
 extern int maxload15;
 extern int minpages;
+extern int minalloc;
 extern int maxtemp;
 extern int pingcount;
 extern int temp_poweroff;
@@ -154,6 +155,7 @@ int check_iface(struct list *);
 int open_memcheck(void);
 int check_memory(void);
 int close_memcheck(void);
+int check_allocatable(void);
 
 /** shutdown.c **/
 void do_shutdown(int errorcode);
diff --git a/src/configfile.c b/src/configfile.c
index 84af048..15891a0 100644
--- a/src/configfile.c
+++ b/src/configfile.c
@@ -35,6 +35,7 @@ static void add_test_binaries(const char *path);
 #define MAXLOAD15		"max-load-15"
 #define MAXTEMP			"max-temperature"
 #define MINMEM			"min-memory"
+#define ALLOCMEM		"allocatable-memory"
 #define SERVERPIDFILE		"pidfile"
 #define PING			"ping"
 #define PINGCOUNT		"ping-count"
@@ -66,6 +67,7 @@ int maxload1 = 0;
 int maxload5 = 0;
 int maxload15 = 0;
 int minpages = 0;
+int minalloc = 0;
 int maxtemp = 120;
 int pingcount = 3;
 int temp_poweroff = TRUE;
@@ -278,6 +280,9 @@ void read_config(char *configfile)
 			} else if (strncmp(line + i, MINMEM, strlen(MINMEM)) == 0) {
 				if (!spool(line, &i, strlen(MINMEM)))
 					minpages = atol(line + i);
+			} else if (strncmp(line + i, ALLOCMEM, strlen(ALLOCMEM)) == 0) {
+				if (!spool(line, &i, strlen(ALLOCMEM)))
+					minalloc = atol(line + i);
 			} else if (strncmp(line + i, LOGDIR, strlen(LOGDIR)) == 0) {
 				if (!spool(line, &i, strlen(LOGDIR)))
 					logdir = xstrdup(line + i);
diff --git a/src/memory.c b/src/memory.c
index d06c99d..9b6f7ef 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -20,6 +20,7 @@
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/param.h>
+#include <sys/mman.h>
 
 #include "extern.h"
 #include "watch_err.h"
@@ -128,3 +129,27 @@ int close_memcheck(void)
 	mem_fd = -1;
 	return rv;
 }
+
+int check_allocatable(void)
+{
+	int i;
+	char *mem;
+
+	if (minalloc <= 0)
+		return 0;
+
+	/*
+	 * Map and fault in the pages
+	 */
+	mem = mmap(NULL, EXEC_PAGESIZE * minalloc, PROT_READ | PROT_WRITE,
+			 MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, 0, 0);
+	if (mem == MAP_FAILED) {
+		i = errno;
+		log_message(LOG_ALERT, "cannot allocate %d bytes (errno = %d)",
+			    EXEC_PAGESIZE * minalloc, i);
+		return i;
+	}
+
+	munmap(mem, EXEC_PAGESIZE * minalloc);
+	return 0;
+}
diff --git a/src/watchdog.c b/src/watchdog.c
index bcc9954..babbece 100644
--- a/src/watchdog.c
+++ b/src/watchdog.c
@@ -415,6 +415,9 @@ int main(int argc, char *const argv[])
 		/* check free memory */
 		do_check(check_memory(), rbinary, NULL);
 
+		/* check allocatable memory */
+		do_check(check_allocatable(), rbinary, NULL);
+
 		/* check temperature */
 		for (act = temp_list; act != NULL; act = act->next)
 			do_check(check_temp(act), rbinary, NULL);
-- 
1.7.9.5