From: Nick Piggin <npiggin@kernel.dk>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Nick Piggin <npiggin@kernel.dk>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: buggy perf callgraph output
Date: Thu, 16 Dec 2010 00:02:45 +1100 [thread overview]
Message-ID: <20101215130245.GA10004@amd> (raw)
In-Reply-To: <20101208214809.GG1709@nowhere>
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.
next prev parent reply other threads:[~2010-12-16 2:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-08 16:40 buggy perf callgraph output Nick Piggin
2010-12-08 21:48 ` Frederic Weisbecker
2010-12-15 13:02 ` Nick Piggin [this message]
2010-12-16 11:47 ` Frederic Weisbecker
2010-12-17 5:32 ` Nick Piggin
2010-12-23 12:55 ` Frederic Weisbecker
2010-12-23 13:08 ` Ingo Molnar
2010-12-23 13:35 ` Frederic Weisbecker
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