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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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