Some dcache_rcu benchmark numbers

Dipankar Sarma
2002-10-14T18:30:17Z

Here are some numbers from the venerable "kernbench" (just kernel compilation)
to indicate how dcache_rcu (currently in -mm) helps us in the larger systems -

A 16-CPU NUMA-Q running make -j 24

2.5.40-mm2 [includes dcache_rcu]
--------------------------------
Elapsed: 19.622s User: 193.366s System: 42.498s CPU: 1201.6% [average of 5]

2.5.40-mm2-no_dcache_rcu
------------------------
Elapsed: 20.47s User: 193.226s System: 47.548s CPU: 1175.8% [average of 5]

IOW, a 10.6% reduction in system time.

In general, we see significant gains with multiuser workloads in
larger systems.

I also did some "kernbench" testing on UP, 2-CPU and 4-CPU configurations
on a PIII xeon based system. The results are included below and they
show that there isn't any regression at the lower end of systems.

Thanks
--
Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.

----------------------------------------------------------------------------
UP :

2.5.42 vanilla
--------------

real 6m12.917s
user 5m48.164s
sys 0m22.677s

real 6m11.102s
user 5m48.103s
sys 0m22.635s

real 6m11.170s
user 5m48.003s
sys 0m22.753s

real 6m11.556s
user 5m48.018s
sys 0m22.728s

real 6m11.137s
user 5m48.185s
sys 0m22.592s

2.5.42 dc12
-----------

real 6m12.965s
user 5m48.261s
sys 0m22.596s

real 6m10.964s
user 5m48.059s
sys 0m22.539s

real 6m11.513s
user 5m48.295s
sys 0m22.402s

real 6m11.139s
user 5m48.040s
sys 0m22.685s

real 6m11.050s
user 5m47.969s
sys 0m22.720s
----------------------------------------------------------------------

2-CPU :

2.5.42 vanilla
--------------

real 3m28.108s
user 6m17.968s
sys 0m29.230s

real 3m25.086s
user 6m17.686s
sys 0m29.307s

real 3m24.832s
user 6m17.966s
sys 0m28.946s

real 3m24.733s
user 6m17.737s
sys 0m29.302s

2.5.42 dc12
-----------

real 3m26.774s
user 6m18.109s
sys 0m29.218s

real 3m25.381s
user 6m17.892s
sys 0m29.155s

real 3m25.719s
user 6m17.708s
sys 0m29.260s

real 3m25.777s
user 6m18.054s
sys 0m28.967s

----------------------------------------------------------------------------

4-CPU :

2.5.42-vanilla
--------------

real 1m47.632s
user 6m25.166s
sys 0m34.480s

real 1m48.780s
user 6m25.250s
sys 0m34.384s

real 1m47.451s
user 6m24.915s
sys 0m34.644s

real 1m48.709s
user 6m25.256s
sys 0m34.688s

real 1m47.797s
user 6m25.193s
sys 0m34.288s

real 1m47.586s
user 6m24.901s
sys 0m34.587s

real 1m47.452s
user 6m25.178s
sys 0m34.272s

real 1m47.969s
user 6m25.285s
sys 0m34.129s

2.5.42-dc12
-----------

real 1m47.638s
user 6m25.450s
sys 0m33.799s

real 1m47.602s
user 6m24.897s
sys 0m34.379s

real 1m48.559s
user 6m25.188s
sys 0m33.941s

real 1m47.945s
user 6m25.345s
sys 0m33.986s

real 1m47.639s
user 6m25.519s
sys 0m33.855s

real 1m48.976s
user 6m25.051s
sys 0m34.189s

real 1m47.447s
user 6m25.383s
sys 0m34.225s

real 1m47.448s
user 6m25.102s
sys 0m33.980s