Eric Lee / smarc-fsl-linux-kernel

02 Apr, 2015

1 commit

  • 9811e3535   samples/bpf: Add kmem_alloc()/free() tracker tool ... Browse Code ยป

    One BPF program attaches to kmem_cache_alloc_node() and
    remembers all allocated objects in the map.
    Another program attaches to kmem_cache_free() and deletes
    corresponding object from the map.

    User space walks the map every second and prints any objects
    which are older than 1 second.

    Usage:

    $ sudo tracex4

    Then start few long living processes. The 'tracex4' will print
    something like this:

    obj 0xffff880465928000 is 13sec old was allocated at ip ffffffff8105dc32
    obj 0xffff88043181c280 is 13sec old was allocated at ip ffffffff8105dc32
    obj 0xffff880465848000 is 8sec old was allocated at ip ffffffff8105dc32
    obj 0xffff8804338bc280 is 15sec old was allocated at ip ffffffff8105dc32

    $ addr2line -fispe vmlinux ffffffff8105dc32
    do_fork at fork.c:1665

    As soon as processes exit the memory is reclaimed and 'tracex4'
    prints nothing.

    Similar experiment can be done with the __kmalloc()/kfree() pair.

    Signed-off-by: Alexei Starovoitov
    Cc: Andrew Morton
    Cc: Arnaldo Carvalho de Melo
    Cc: Arnaldo Carvalho de Melo
    Cc: Daniel Borkmann
    Cc: David S. Miller
    Cc: Jiri Olsa
    Cc: Linus Torvalds
    Cc: Masami Hiramatsu
    Cc: Namhyung Kim
    Cc: Peter Zijlstra
    Cc: Peter Zijlstra
    Cc: Steven Rostedt
    Link: http://lkml.kernel.org/r/1427312966-8434-10-git-send-email-ast@plumgrid.com
    Signed-off-by: Ingo Molnar

    Alexei Starovoitov