Re: Lockdep usage
From: Darren Hart
Date: Thu Apr 22 2010 - 10:57:54 EST
Yong Zhang wrote:
On Wed, Apr 21, 2010 at 11:26:07PM -0700, Darren Hart wrote:
I'm having some trouble with lockstat. I've enabled
CONFIG_LOCK_STATS and then run the following commands to collect the
lock statistics for the futex_lock test case. I expect this test
case to generate a fair amount of contention on the futex hash
bucket locks, but they don't show up in the stats (in fact, nothing
shows up in the stats). I have seen much longer lock_stat files when
I forgot to clear them before the test, but no hb locks showed up
there either.
Is my usage below incorrect? Do I have to somehow annotate the
hb->lock in order for lockstat to track it?
IMHO, you don't need to do that.
lock.lockstat; echo 0 > /proc/sys/kernel/lock_stat
futex_lock: Measure FUTEX_LOCK operations per second
Arguments: iterations=10000000 threads=256 adaptive=no
period=1000 duty-cycle=20%
Result: 731 Kiter/s
# cat lock.lockstat
lock_stat version 0.3
*WARNING* lock debugging disabled!! - possibly due to a lockdep warning
This means lockdep has detect there is something wrong.
Can you show your 'dmesg'?
dmesg includes the following during bootup, but nothing new while
running the tests:
BUG: key ffff88024e657858 not in .data!
------------[ cut here ]------------
WARNING: at kernel/lockdep.c:2706 lockdep_init_map+0x226/0x5c0()
Hardware name: BladeCenter LS21 -[7971AC1]-
Pid: 1, comm: swapper Not tainted 2.6.34-rc1dvhv4ls #32
Call Trace:
[<ffffffff81078446>] ? lockdep_init_map+0x226/0x5c0
[<ffffffff81048687>] warn_slowpath_common+0x87/0xb0
[<ffffffff810486c4>] warn_slowpath_null+0x14/0x20
[<ffffffff81078446>] lockdep_init_map+0x226/0x5c0
[<ffffffff81077f53>] ? lock_release_holdtime+0x83/0xf0
[<ffffffff8115e5a1>] sysfs_add_file_mode+0x71/0xd0
[<ffffffff8115e611>] sysfs_add_file+0x11/0x20
[<ffffffff8115e650>] sysfs_create_file+0x30/0x40
[<ffffffff814995d9>] device_create_file+0x19/0x20
[<ffffffff813afe55>] ipmi_register_smi+0xba5/0xfc0
[<ffffffff81498877>] ? put_device+0x17/0x20
[<ffffffff810670d0>] ? autoremove_wake_function+0x0/0x40
[<ffffffff813b3a12>] try_smi_init+0x5d2/0xa20
[<ffffffff818d5b72>] init_ipmi_si+0x432/0xb80
[<ffffffff818d5740>] ? init_ipmi_si+0x0/0xb80
[<ffffffff810001dd>] do_one_initcall+0x3d/0x180
[<ffffffff822d5a6c>] kernel_init+0x16c/0x200
[<ffffffff81003c14>] kernel_thread_helper+0x4/0x10
[<ffffffff822d5900>] ? kernel_init+0x0/0x200
[<ffffffff81003c10>] ? kernel_thread_helper+0x0/0x10
---[ end trace 30838b0dc5ec48e4 ]---
Several more "BUG: key fffXXXXXXXXXXXX not in .data!" lines show up
throughout the boot process.
I vaguely recall this being normal for lockstat at initial boot.
--
Darren
Thanks,
Yong
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
class name con-bounces
contentions waittime-min waittime-max waittime-total
acq-bounces acquisitions holdtime-min holdtime-max
holdtime-total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
#
Thanks,
--
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team
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--
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team
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