Re: kernbench on 512p

Maneesh Soni
2004-08-20T19:38:42Z

On Thu, Aug 19, 2004 at 02:56:39PM -0700, Martin J. Bligh wrote:
> --On Thursday, August 19, 2004 17:24:04 -0400 Jesse Barnes <jbarnes@engr.sgi.com> wrote:
>
> > On Thursday, August 19, 2004 5:11 pm, Jesse Barnes wrote:
> >> The output is attached (my mailer insists on wrapping it if I inline it).
> >> I used 'lockstat -w'.
> >
> > The highlights:
> >
> > nw spin rjct lock & function
> > 19.0% 81.0% 0% dcache_lock
> > 3.3% 96.7% 0% d_alloc+0x270
> > 2.7% 97.3% 0% d_delete+0x40
> > 18.3% 81.7% 0% d_instantiate+0x90
> > 4.7% 95.3% 0% d_move+0x60
> > 34.6% 65.4% 0% d_rehash+0xe0
> > 19.1% 80.9% 0% dput+0x40
> > 10.5% 89.5% 0% link_path_walk+0xef0
> > 0% 100% 0% sys_getcwd+0x210
> >
> > 41.4% 58.6% 0% rcu_state
> > 61.3% 38.7% 0% __rcu_process_callbacks+0x260
> > 41.4% 58.6% 0% rcu_check_quiescent_state+0xf0
> >
> > So it looks like the dcache lock is the biggest problem on this system with
> > this load. And although the rcu stuff has improved tremendously for this
> > system, it's still highly contended.
>
> Hmmm. dcache_lock is known-fucked, though I'm suprised at d_rehash
> (file deletion)?
>

The thing which is hurting most is dput(), almost 90% of the dcache_lock
aquistion is there.

(deleted few columns)

23.8% 67.3% 9955785 32.7% 67.3% 0% dcache_lock
0.06% 70.5% 17068 29.5% 70.5% 0% d_alloc+0x270
0.02% 25.4% 15340 74.6% 25.4% 0% d_delete+0x40
0.06% 65.9% 30485 34.1% 65.9% 0% d_instantiate+0x90
0.06% 78.0% 4461 22.0% 78.0% 0% d_move+0x60
0.00% 0% 2 100% 0% 0% d_path+0x120
0.04% 52.5% 17068 47.5% 52.5% 0% d_rehash+0xe0
0.00% 26.7% 15 73.3% 26.7% 0% d_splice_alias+0xc0
0.00% 20.0% 5 80.0% 20.0% 0% dentry_unhash+0x70
0.00% 0% 4 100% 0% 0% dentry_unhash+0xc0
23.5% 67.5% 9827270 32.5% 67.5% 0% dput+0x40
0.09% 62.3% 36875 37.7% 62.3% 0% link_path_walk+0xef0
0.00% 0.24% 5068 99.8% 0.24% 0% link_path_walk+0x1cc0
0.00% 33.3% 3 66.7% 33.3% 0% proc_pid_unhash+0x50
0.00% 7.1% 14 92.9% 7.1% 0% prune_dcache+0x50
0.00% 0% 167 100% 0% 0% prune_dcache+0x3d0
0.00% 0% 21 100% 0% 0% select_parent+0x40
0.00% 24.2% 1919 75.8% 24.2% 0% sys_getcwd+0x210

--
Maneesh Soni
Linux Technology Center,
IBM Austin
email: maneesh@in.ibm.com
Phone: 1-512-838-1896 Fax:
T/L : 6781896