• Arnaldo Carvalho de Melo's avatar
    perf trace: Beautify statx syscall 'flag' and 'mask' arguments · fd5cead2
    Arnaldo Carvalho de Melo authored
    To test it, build samples/statx/test_statx, which I did as:
    
      $ make headers_install
      $ cc -I ~/git/linux/usr/include samples/statx/test-statx.c -o /tmp/statx
    
    And then use perf trace on it:
    
      # perf trace -e statx /tmp/statx /etc/passwd
      statx(/etc/passwd) = 0
      results=7ff
        Size: 3496            Blocks: 8          IO Block: 4096    regular file
      Device: fd:00           Inode: 280156      Links: 1
      Access: (0644/-rw-r--r--)  Uid:     0   Gid:     0
      Access: 2017-03-29 16:01:01.650073438-0300
      Modify: 2017-03-10 16:25:14.156479354-0300
      Change: 2017-03-10 16:25:14.171479328-0300
         0.000 ( 0.007 ms): statx/30648 statx(dfd: CWD, filename: 0x7ef503f4, flags: SYMLINK_NOFOLLOW, mask: TYPE|MODE|NLINK|UID|GID|ATIME|MTIME|CTIME|INO|SIZE|BLOCKS|BTIME, buffer: 0x7fff7ef4eb10) = 0
      #
    
    Using the test-stat.c options to change the mask:
    
      # perf trace -e statx /tmp/statx -O /etc/passwd > /dev/null
         0.000 ( 0.008 ms): statx/30745 statx(dfd: CWD, filename: 0x3a0753f4, flags: SYMLINK_NOFOLLOW, mask: BTIME, buffer: 0x7ffd3a0735c0) = 0
      #
      # perf trace -e statx /tmp/statx -A /etc/passwd > /dev/null
         0.000 ( 0.010 ms): statx/30757 statx(dfd: CWD, filename: 0xa94e63f4, flags: SYMLINK_NOFOLLOW|NO_AUTOMOUNT, mask: TYPE|MODE|NLINK|UID|GID|ATIME|MTIME|CTIME|INO|SIZE|BLOCKS|BTIME, buffer: 0x7ffea94e49d0) = 0
      #
      # trace --no-inherit -e statx /tmp/statx -F /etc/passwd > /dev/null
         0.000 ( 0.011 ms): statx(dfd: CWD, filename: 0x3b02d3f3, flags: SYMLINK_NOFOLLOW|STATX_FORCE_SYNC, mask: TYPE|MODE|NLINK|UID|GID|ATIME|MTIME|CTIME|INO|SIZE|BLOCKS|BTIME, buffer: 0x7ffd3b02c850) = 0
      #
      # trace --no-inherit -e statx /tmp/statx -F -L /etc/passwd > /dev/null
         0.000 ( 0.008 ms): statx(dfd: CWD, filename: 0x15cff3f3, flags: STATX_FORCE_SYNC, mask: TYPE|MODE|NLINK|UID|GID|ATIME|MTIME|CTIME|INO|SIZE|BLOCKS|BTIME, buffer: 0x7fff15cfdda0) = 0
      #
      # trace --no-inherit -e statx /tmp/statx -D -O /etc/passwd > /dev/null
         0.000 ( 0.009 ms): statx(dfd: CWD, filename: 0xfa37f3f3, flags: SYMLINK_NOFOLLOW|STATX_DONT_SYNC, mask: BTIME, buffer: 0x7ffffa37da20) = 0
      #
    
    Adding a probe to get the filename collected as well:
    
      # perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string'
      Added new event:
        probe:vfs_getname    (on getname_flags:72 with pathname=result->name:string)
    
      You can now use it in all perf tools, such as:
    
    	  perf record -e probe:vfs_getname -aR sleep 1
    
      # trace --no-inherit -e statx /tmp/statx -D -O /etc/passwd > /dev/null
         0.169 ( 0.007 ms): statx(dfd: CWD, filename: /etc/passwd, flags: SYMLINK_NOFOLLOW|STATX_DONT_SYNC, mask: BTIME, buffer: 0x7ffda9bf50f0) = 0
      #
    
    Same technique could be used to collect and beautify the result put in
    the 'buffer' argument.
    
    Finally do a system wide 'perf trace' session looking for any use of statx,
    then run the test proggie with various flags:
    
      # trace -e statx
       16612.967 ( 0.028 ms): statx/4562 statx(dfd: CWD, filename: /tmp/statx, flags: SYMLINK_NOFOLLOW, mask: TYPE|MODE|NLINK|UID|GID|ATIME|MTIME|CTIME|INO|SIZE|BLOCKS|BTIME, buffer: 0x7ffef195d660) = 0
       33064.447 ( 0.011 ms): statx/4569 statx(dfd: CWD, filename: /tmp/statx, flags: SYMLINK_NOFOLLOW|STATX_FORCE_SYNC, mask: TYPE|MODE|NLINK|UID|GID|ATIME|MTIME|CTIME|INO|SIZE|BLOCKS|BTIME, buffer: 0x7ffc5484c790) = 0
       36050.891 ( 0.023 ms): statx/4576 statx(dfd: CWD, filename: /tmp/statx, flags: SYMLINK_NOFOLLOW, mask: BTIME, buffer: 0x7ffeb18b66e0) = 0
       38039.889 ( 0.023 ms): statx/4584 statx(dfd: CWD, filename: /tmp/statx, flags: SYMLINK_NOFOLLOW, mask: TYPE|MODE|NLINK|UID|GID|ATIME|MTIME|CTIME|INO|SIZE|BLOCKS|BTIME, buffer: 0x7fff1db0ea90) = 0
      ^C#
    
    This one also starts moving the beautifiers from files directly included
    in builtin-trace.c to separate objects + a beauty.h header with
    prototypes, so that we can add test cases in tools/perf/tests/ to fire
    syscalls with various arguments and then get them intercepted as
    syscalls:sys_enter_foo or raw_syscalls:sys_enter + sys_exit to then
    format and check that the formatted output is the one we expect.
    
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: David Howells <dhowells@redhat.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Wang Nan <wangnan0@huawei.com>
    Link: http://lkml.kernel.org/n/tip-xvzw8eynffvez5czyzidhrno@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    fd5cead2
statx.c 1.56 KB