Re: kernbench on 512p

Martin J. Bligh
2004-08-19T21:57:51Z

--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)?

RCU stuff is a bit sad.

M.