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    SubjectRe: buggy perf callgraph output
    On Wed, Dec 08, 2010 at 10:48:13PM +0100, Frederic Weisbecker wrote:
    > I can not reproduce it. Could you please try to reproduce,
    > run perf archive and send me your perf.data.tar.bz2 ?

    It seems to be happening all the time, just look further in
    callgraphs.

    This attached perf.data.bz2 looks like this, when using -g graph

    15.05% dbench [kernel.kallsyms] [k]
    copy_user_generic_string
    |
    --- copy_user_generic_string
    |
    |---0.16%-- generic_file_aio_read
    | do_sync_read
    | vfs_read
    | |
    | --0.05%-- sys_pread64
    | system_call
    | 0x7f64a60bb193
    |
    |--0.10%-- generic_file_buffered_write
    | __generic_file_aio_write
    | generic_file_aio_write
    | do_sync_write
    | vfs_write
    | sys_pwrite64
    | system_call
    | 0x7f64a60bb203
    | 0xe01170
    |
    ---0.11%-- dcache_readdir
    vfs_readdir
    sys_getdents
    system_call
    0x7f64a60ade65

    See, the last element is greater than the second last.

    -g fractal looks like this:

    15.05% dbench [kernel.kallsyms] [k]
    copy_user_generic_string
    |
    --- copy_user_generic_string
    |
    |---1.09%-- generic_file_aio_read
    | do_sync_read
    | vfs_read
    | |
    | |--0.55%-- sys_pread64
    | | system_call
    | | 0x7f64a60bb193
    | |
    | --2.19%-- sys_read
    | system_call
    | 0x7f64a60d3ea0
    |
    |--0.69%-- generic_file_buffered_write
    | __generic_file_aio_write
    | generic_file_aio_write
    | do_sync_write
    | vfs_write
    | sys_pwrite64
    | system_call
    | 0x7f64a60bb203
    | 0xe01170
    |
    |---0.72%-- dcache_readdir
    | vfs_readdir
    | sys_getdents
    | system_call
    | 0x7f64a60ade65


    So it's totally screwy.



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