vfscount.py: add args time (iovisor#2344)

add args time for vfscount.py

man/man8/vfscount.8

@@ -19,6 +19,10 @@ CONFIG_BPF and bcc.
 Count some VFS calls until Ctrl-C is hit:
 #
 .B vfscount
+.TP
+Count some VFS calls in ten seconds
+#
+.B vfscount 10
 .SH FIELDS
 .TP
 ADDR

tools/vfscount.py

@@ -14,7 +14,19 @@
 from __future__ import print_function
 from bcc import BPF
 from time import sleep
-
+from sys import argv
+def usage():
+ print("USAGE: %s [time]" % argv[0])
+ exit()
+
+interval = 99999999
+if len(argv) > 1:
+ try:
+ interval = int(argv[1])
+ if interval == 0:
+ raise
+ except: # also catches -h, --help
+ usage()
 # load BPF program
 b = BPF(text="""
 #include <uapi/linux/ptrace.h>
@@ -39,9 +51,10 @@
 
 # output
 try:
- sleep(99999999)
+ sleep(interval)
 except KeyboardInterrupt:
  pass
+ exit()
 
 print("\n%-16s %-26s %8s" % ("ADDR", "FUNC", "COUNT"))
 counts = b.get_table("counts")

tools/vfscount_example.txt

@@ -1,8 +1,8 @@
 Demonstrations of vfscount, the Linux eBPF/bcc version.
 
 
-This counts VFS calls, by tracing all kernel functions beginning with "vfs_":
-
+This counts VFS calls during time, by tracing all kernel functions beginning 
+with "vfs_", By defaults, the time is 99999999s
 # ./vfscount
 Tracing... Ctrl-C to end.
 ^C
@@ -20,7 +20,36 @@ ffffffff811ec9f1 vfs_getattr_nosec 704
 ffffffff811e80a1 vfs_write 1764
 ffffffff811e7f71 vfs_read 2283
 
+Here we are using an output in 10 seconds, and printing 10 seconds summaries
+# ./vfscount 10
+Tracing... Ctrl-C to end.
+
+ADDR FUNC COUNT
+ffffffffa1283671 vfs_rename 1
+ffffffffa129f471 vfs_setxattr 1
+ffffffffa12831c1 vfs_mkdir 1
+ffffffffa1282a51 vfs_rmdir 10
+ffffffffa1283f31 vfs_unlink 28
+ffffffffa1273e61 vfs_writev 53
+ffffffffa12ae061 vfs_statfs 55
+ffffffffa129e971 vfs_getxattr 138
+ffffffffa1288561 vfs_readlink 157
+ffffffffa12d6311 vfs_lock_file 223
+ffffffffa1274da1 vfs_write 537
+ffffffffa12798f1 vfs_statx_fd 2337
+ffffffffa1279971 vfs_statx 3064
+ffffffffa1271ba1 vfs_open 4334
+ffffffffa12798b1 vfs_getattr 4823
+ffffffffa1279821 vfs_getattr_nosec 4823
+ffffffffa1274af1 vfs_read 9060
+
+
 This can be useful for workload characterization, to see what types of
 operations are in use.
 
 You can edit the script to customize what kernel functions are matched.
+
+Full usage:
+
+# ./vfsstat -h
+USAGE: ./vfsstat [time]