On Wed, Aug 10, 2011 at 07:51:14AM -0700, Adam Leventhal wrote:
> Hey Przemek,
>
> 1. Since you're not seeing any contention probes fire, it's not
> surprising that you never (rarely) see output from plockstat.
Just a few minutes ago I did:
# plockstat -x dynvarsize=200m -x aggsize=200m -A -e 5 -n 5 -s 30 -p 20943
0
Mutex hold
-------------------------------------------------------------------------------
Count nsec Lock Caller
24 68266 libc.so.1`libc_malloc_lock libodm.so.1`odm_io+0x5c
nsec ---- Time Distribution --- count Stack
65536 |@@@@@@@@@@@@@@@@@@@@@@@ | 23 libc.so.1`malloc+0x6c
131072 |@ | 1 libodm.so.1`odm_io+0x5c
oracle`ksfd_odmwat+0x2ac
oracle`ksfdwtio+0x464
oracle`ksfdwat1+0x94
oracle`ksfdrwat0+0x220
oracle`kcflci+0x1c
oracle`kcblco+0x6c
> 2. I've confirmed with an Oracle user that the database indeed rolls
> its own locking primitives.
>
> 3. I imagine that the lock events that you're seeing are internal to
> various libraries. You can confirm this by running the following
> script:
>
> dtrace -p <pid> -n 'plockstat$target:::{ @[probename, ustack()] = count(); }'
Since the output is quite long I give a part of it:
mutex-acquire
libc.so.1`mutex_lock_impl+0xc0
--
1
mutex-acquire
libc.so.1`mutex_lock_impl+0xc0
--
1
mutex-acquire
libc.so.1`mutex_lock_impl+0xc0
--
1
mutex-acquire
libc.so.1`mutex_lock_impl+0xc0
--
...
mutex-release
libc.so.1`mutex_unlock+0xc8
--
1
mutex-release
libc.so.1`mutex_unlock+0xc8
--
1
mutex-release
libc.so.1`mutex_unlock+0xc8
--
1
mutex-release
libc.so.1`mutex_unlock+0xc8
--
1
mutex-release
libc.so.1`mutex_unlock+0xc8
...
mutex-release
libc.so.1`mutex_unlock+0xc8
--
160
mutex-release
libc.so.1`mutex_unlock+0xc8
--
160
mutex-release
libc.so.1`mutex_unlock+0xc8
--
160
mutex-release
libc.so.1`mutex_unlock+0xc8
--
160
mutex-release
libc.so.1`lmutex_unlock+0x38
mutex-release
libc.so.1`lmutex_unlock+0x38
libc.so.1`localtime_r+0xc4
oracle`slgtds+0x2c
oracle`slgtd+0xc
oracle`kcmgts+0xc
oracle`kcblgr+0x924
oracle`kcblio+0x154
oracle`kcblnb+0x420
oracle`kdblnb+0x54
oracle`kdblailb+0x7e4
oracle`kdblai+0x528
oracle`klclil1r+0xb4
oracle`qerltRop+0x258
oracle`qerrmPFR+0x1f4
oracle`qerrmOdcb+0x4
oracle`ttcfour+0x1fd4
oracle`ttcdrv+0x4f4
oracle`nioqwa+0x3c
oracle`upirtrc+0x484
oracle`kpurcsc+0x70
160
Regards
Przemek
----------------------------------------------------------------
Dziesiatki tysiecy ofert domow i mieszkan!
Ogladaj >> http://linkint.pl/f2a0c
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