From: Ben Pfaff <blp@cs.stanford.edu>
Date: Wed, 15 Mar 2006 22:15:40 +0000 (+0000)
Subject: Make timeouts based on CPU time.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bb7e71ecaa84d1dc223e5372e804ba6c9d5bfb00;p=pintos-anon

Make timeouts based on CPU time.
---

diff --git a/src/utils/Makefile b/src/utils/Makefile
new file mode 100644
index 0000000..9eca3ba
--- /dev/null
+++ b/src/utils/Makefile
@@ -0,0 +1,7 @@
+all: setitimer-helper
+
+LDFLAGS = -lm
+setitimer-helper: setitimer-helper.o
+
+clean: 
+	rm -f *.o setitimer-helper
diff --git a/src/utils/README b/src/utils/README
new file mode 100644
index 0000000..004478f
--- /dev/null
+++ b/src/utils/README
@@ -0,0 +1,6 @@
+If your version of Perl predates 5.8.0, then you will need to compile
+setitimer-helper (with `make') and install it in PATH, if you want the
+"pintos" script's timeout support (with -T) to properly limit the
+child's CPU time.  Otherwise, it is unneeded.
+
+- Ben
diff --git a/src/utils/pintos b/src/utils/pintos
index f993968..83954bb 100755
--- a/src/utils/pintos
+++ b/src/utils/pintos
@@ -7,6 +7,7 @@ use File::Temp 'tempfile';
 use Getopt::Long qw(:config bundling);
 
 # Command-line options.
+our ($start_time) = time ();
 our ($sim);			# Simulator: bochs, qemu, or gsx.
 our ($debug) = "none";		# Debugger: none, monitor, or gdb.
 our ($mem) = 4;			# Physical RAM in MB.
@@ -111,7 +112,8 @@ Display options: (default is both VGA and serial)
 Timing options: (Bochs only)
   -j SEED                  Randomize timer interrupts
   -r, --realtime           Use realistic, not reproducible, timings
-  -T, --timeout=N          Time out and kill Pintos after N seconds
+  -T, --timeout=N          Kill Pintos after N seconds CPU time or N*load_avg
+                           seconds wall-clock time (whichever comes first)
 Configuration options:
   -m, --mem=N              Give Pintos N MB physical RAM (default: 4)
 File system commands (for `run' command):
@@ -660,16 +662,22 @@ sub xsystem {
 	die "fork: $!\n";
     } elsif (!$pid) {
 	# Running in child process.
-	exec (@_);
-	exit (1);
+	exec_setitimer (@_);
     } else {
 	# Running in parent process.
 	local $SIG{ALRM} = sub { timeout ($pid); };
 	local $SIG{INT} = sub { relay_signal ($pid, "INT"); };
 	local $SIG{TERM} = sub { relay_signal ($pid, "TERM"); };
-	alarm ($timeout) if defined ($timeout);
+	alarm ($timeout * get_load_average () + 1) if defined ($timeout);
 	waitpid ($pid, 0);
 	alarm (0);
+
+	if (WIFSIGNALED ($?) && WTERMSIG ($?) == SIGVTALRM ()) {
+	    seek (STDOUT, 0, 2);
+	    print "\nTIMEOUT after $timeout seconds of host CPU time\n";
+	    exit 0;
+	}
+
 	return $?;
     }
 }
@@ -695,8 +703,45 @@ sub timeout {
     waitpid ($pid, 0);
     seek (STDOUT, 0, 2);
     my ($load_avg) = `uptime` =~ /(load average:.*)$/i;
-    print "\nTIMEOUT after $timeout seconds";
+    print "\nTIMEOUT after ", time () - $start_time,
+      " seconds of wall-clock time";
     print  " - $load_avg" if defined $load_avg;
     print "\n";
     exit 0;
 }
+
+# Returns the system load average over the last minute.
+# If the load average is less than 1.0 or cannot be determined, returns 1.0.
+sub get_load_average {
+    my ($avg) = `uptime` =~ /load average:\s*([^,]+),/;
+    return $avg >= 1.0 ? $avg : 1.0;
+}
+
+# Calls setitimer to set a timeout, then execs what was passed to us.
+sub exec_setitimer {
+    if (defined $timeout) {
+	if ($ ge 5.8.0) {
+	    eval "
+              use Time::HiRes qw(setitimer ITIMER_VIRTUAL);
+              setitimer (ITIMER_VIRTUAL, $timeout, 0);
+            ";
+	} else {
+	    { exec ("setitimer-helper", $timeout, @_); };
+	    exit 1 if !$!{ENOENT};
+	    print STDERR "warning: setitimer-helper is not installed, so ",
+	      "CPU time limit will not be enforced\n";
+	}
+    }
+    exec (@_);
+    exit (1);
+}
+
+sub SIGVTALRM {
+    use Config;
+    my $i = 0;
+    foreach my $name (split(' ', $Config{sig_name})) {
+	return $i if $name eq 'VTALRM';
+	$i++;
+    }
+    return 0;
+}
diff --git a/src/utils/setitimer-helper.c b/src/utils/setitimer-helper.c
new file mode 100644
index 0000000..772d736
--- /dev/null
+++ b/src/utils/setitimer-helper.c
@@ -0,0 +1,49 @@
+#include <errno.h>
+#include <limits.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+int
+main (int argc, char *argv[]) 
+{
+  const char *program_name = argv[0];
+  double timeout;
+
+  if (argc < 3)
+    {
+      fprintf (stderr,
+               "setitimer-helper: runs a program with a virtual CPU limit\n"
+               "usage: %s TIMEOUT PROGRAM [ARG...]\n"
+               "  where TIMEOUT is the virtual CPU limit, in seconds,\n"
+               "    and remaining arguments specify the program to run\n"
+               "    and its argument.\n",
+               program_name);
+      return EXIT_FAILURE;
+    }
+
+  timeout = strtod (argv[1], NULL);
+  if (timeout >= 0.0 && timeout < LONG_MAX)
+    {
+      struct itimerval it;
+
+      it.it_interval.tv_sec = 0;
+      it.it_interval.tv_usec = 0;
+      it.it_value.tv_sec = timeout;
+      it.it_value.tv_usec = (timeout - floor (timeout)) * 1000000;
+      if (setitimer (ITIMER_VIRTUAL, &it, NULL) < 0)
+        fprintf (stderr, "%s: setitimer: %s\n",
+                 program_name, strerror (errno));
+    }
+  else
+    fprintf (stderr, "%s: invalid timeout value \"%s\"\n",
+             program_name, argv[1]);
+  
+  execvp (argv[2], &argv[2]);
+  fprintf (stderr, "%s: couldn't exec \"%s\": %s\n",
+           program_name, argv[2], strerror (errno));
+  return EXIT_FAILURE;
+}