funccount: add -d for duration

man/man8/funccount.8

@@ -27,6 +27,9 @@ Trace this process ID only.
 \-i INTERVAL
 Print output every interval seconds.
 .TP
+\-d DURATION
+Total duration of trace in seconds.
+.TP
 \-T
 Include timestamps on output.
 .TP
@@ -49,6 +52,10 @@ Print kernel functions beginning with "vfs_", every second:
 #
 .B funccount \-i 1 'vfs_*'
 .TP
+Print kernel functions beginning with "vfs_", for ten seconds only:
+#
+.B funccount \-d 10 'vfs_*'
+.TP
 Match kernel functions beginning with "vfs_", using regular expressions:
 #
 .B funccount \-r '^vfs_.*'

tools/funccount.py

@@ -4,7 +4,7 @@
 # funccount Count functions, tracepoints, and USDT probes.
 #           For Linux, uses BCC, eBPF.
 #
-# USAGE: funccount [-h] [-p PID] [-i INTERVAL] [-T] [-r] pattern
+# USAGE: funccount [-h] [-p PID] [-i INTERVAL] [-d DURATION] [-T] [-r] pattern
 #
 # The pattern is a string with optional '*' wildcards, similar to file
 # globbing. If you'd prefer to use regular expressions, use the -r option.
@@ -218,6 +218,7 @@ class Tool(object):
     ./funccount 'vfs_*'             # count kernel fns starting with "vfs"
     ./funccount -r '^vfs.*'         # same as above, using regular expressions
     ./funccount -Ti 5 'vfs_*'       # output every 5 seconds, with timestamps
+    ./funccount -d 10 'vfs_*'       # trace for 10 seconds only
     ./funccount -p 185 'vfs_*'      # count vfs calls for PID 181 only
     ./funccount t:sched:sched_fork  # count calls to the sched_fork tracepoint
     ./funccount -p 185 u:node:gc*   # count all GC USDT probes in node, PID 185
@@ -232,13 +233,15 @@ class Tool(object):
             epilog=examples)
         parser.add_argument("-p", "--pid", type=int,
             help="trace this PID only")
-        parser.add_argument("-i", "--interval", default=99999999,
+        parser.add_argument("-i", "--interval",
             help="summary interval, seconds")
+        parser.add_argument("-d", "--duration",
+            help="total duration of trace, seconds")
         parser.add_argument("-T", "--timestamp", action="store_true",
             help="include timestamp on output")
         parser.add_argument("-r", "--regexp", action="store_true",
             help="use regular expressions. Default is \"*\" wildcards only.")
-        parser.add_argument("-d", "--debug", action="store_true",
+        parser.add_argument("-D", "--debug", action="store_true",
             help="print BPF program before starting (for debugging purposes)")
         parser.add_argument("pattern",
             help="search expression for events")
@@ -246,6 +249,10 @@ class Tool(object):
         global debug
         debug = self.args.debug
         self.probe = Probe(self.args.pattern, self.args.regexp, self.args.pid)
+        if self.args.duration and not self.args.interval:
+            self.args.interval = self.args.duration
+        if not self.args.interval:
+            self.args.interval = 99999999
 
     @staticmethod
     def _signal_ignore(signal, frame):
@@ -257,13 +264,17 @@ class Tool(object):
         print("Tracing %d functions for \"%s\"... Hit Ctrl-C to end." %
               (self.probe.matched, self.args.pattern))
         exiting = 0 if self.args.interval else 1
+        seconds = 0
         while True:
             try:
                 sleep(int(self.args.interval))
+                seconds += int(self.args.interval)
             except KeyboardInterrupt:
                 exiting = 1
                 # as cleanup can take many seconds, trap Ctrl-C:
                 signal.signal(signal.SIGINT, Tool._signal_ignore)
+            if self.args.duration and seconds >= int(self.args.duration):
+                exiting = 1
 
             print()
             if self.args.timestamp:

tools/funccount_example.txt

@@ -266,6 +266,41 @@ kernel activity that aren't visible in other metrics.
 Include -T to print timestamps on output.
 
 
+A maximum duration can be set. For example, to print 5 x 1 second summaries
+of vfs_read() calls:
+
+# ./funccount -i 1 -d 5 vfs_read
+Tracing 1 functions for "vfs_read"... Hit Ctrl-C to end.
+
+FUNC                                    COUNT
+vfs_read                                   30
+
+FUNC                                    COUNT
+vfs_read                                   26
+
+FUNC                                    COUNT
+vfs_read                                   54
+
+FUNC                                    COUNT
+vfs_read                                   25
+
+FUNC                                    COUNT
+vfs_read                                   31
+Detaching...
+
+By leaving off the "-i 1", this will print a single 5 second summary:
+
+# funccount.py -d 5 vfs_read
+Tracing 1 functions for "vfs_read"... Hit Ctrl-C to end.
+
+FUNC                                    COUNT
+vfs_read                                  167
+Detaching...
+
+This can be useful for finding out rates: trace all functions for ten seconds
+and then divide by ten for the per-second rate.
+
+
 The "*" wildcard can be used multiple times. Eg, matching functions that contain
 the word "readdir":
 
@@ -293,8 +328,9 @@ Detaching...
 
 Full USAGE:
 
-# ./funccount  -h
-usage: funccount.py [-h] [-p PID] [-i INTERVAL] [-T] [-r] [-d] pattern
+# ./funccount -h
+usage: funccount [-h] [-p PID] [-i INTERVAL] [-d DURATION] [-T] [-r] [-D]
+                    pattern
 
 Count functions, tracepoints, and USDT probes
 
@@ -306,16 +342,19 @@ optional arguments:
   -p PID, --pid PID     trace this PID only
   -i INTERVAL, --interval INTERVAL
                         summary interval, seconds
+  -d DURATION, --duration DURATION
+                        total duration of trace, seconds
   -T, --timestamp       include timestamp on output
   -r, --regexp          use regular expressions. Default is "*" wildcards
                         only.
-  -d, --debug           print BPF program before starting (for debugging
+  -D, --debug           print BPF program before starting (for debugging
                         purposes)
 
 examples:
     ./funccount 'vfs_*'             # count kernel fns starting with "vfs"
     ./funccount -r '^vfs.*'         # same as above, using regular expressions
     ./funccount -Ti 5 'vfs_*'       # output every 5 seconds, with timestamps
+    ./funccount -d 10 'vfs_*'       # trace for 10 seconds only
     ./funccount -p 185 'vfs_*'      # count vfs calls for PID 181 only
     ./funccount t:sched:sched_fork  # count calls to the sched_fork tracepoint
     ./funccount -p 185 u:node:gc*   # count all GC USDT probes in node, PID 185