Add pidstat support

pidstat is a script that comes from sysstat, but will give us
per-process information.  Allow enabling "pidstat" that will run pidstat
to give info every 5 seconds by default.

Change-Id: I5ec7d5abce81125b55985bba3ccaf8073ccdfa2a
diff --git a/stack.sh b/stack.sh
index efdee64..1d02c16 100755
--- a/stack.sh
+++ b/stack.sh
@@ -291,6 +291,9 @@
 SYSSTAT_FILE=${SYSSTAT_FILE:-"sysstat.dat"}
 SYSSTAT_INTERVAL=${SYSSTAT_INTERVAL:-"1"}
 
+PIDSTAT_FILE=${PIDSTAT_FILE:-"pidstat.txt"}
+PIDSTAT_INTERVAL=${PIDSTAT_INTERVAL:-"5"}
+
 # Use color for logging output (only available if syslog is not used)
 LOG_COLOR=`trueorfalse True $LOG_COLOR`
 
@@ -874,6 +877,16 @@
     fi
 fi
 
+if is_service_enabled pidstat; then
+    # Per-process stats
+    PIDSTAT_OPTS="-l -p ALL -T ALL"
+    if [[ -n ${SCREEN_LOGDIR} ]]; then
+        screen_it pidstat "cd $TOP_DIR; pidstat $PIDSTAT_OPTS $PIDSTAT_INTERVAL > $SCREEN_LOGDIR/$PIDSTAT_FILE"
+    else
+        screen_it pidstat "pidstat $PIDSTAT_OPTS $PIDSTAT_INTERVAL"
+    fi
+fi
+
 
 # Start Services
 # ==============