[Gems-users] Question about execution slowdown due to Ruby

[Mark Gebhart <mgebhart@xxxxxxxxxxxxx>]

Hi,

I am running some tests using MOSI_SMP_bcast with a 4 processor target
machine using cashew-common.simics.  I have set the memory size in both Ruby
and the simics config file to 4 GB.

I wrote a short vector add test program and compared the time to simulate on
simics with and without Ruby loaded.  Ruby+simics is between 2000 and 3000
times slower than just simics.  I changed all of the cache latencies to be 1
cycle and then Ruby+simcs was between 200 and 300 times slower than just
simcs.  Are these slowdowns in line with what others have observed?  I saw
in an archived message on this list that perhaps a slowdown closer to 10x
would be expected.

I am using simics 3.0-22 and GEMS 1.3, my host machine is a 2.8 GHZ P4 with
1G of RAM and nothing else running during simulation.   The simics process
stays at 100% utilization throughout the execution.

I have compiled Ruby with the following optimization flags:
-O2 -finline-functions -DNO_VECTOR_BOUNDS_CHECKS -DMULTIFACET_NO_OPT_WARN

I use the -stall flag to simics and then issue the following commands:

read-configuration ../../checkpoints-u3/linux-a.out-sun-4p.check
instruction-fetch-mode instruction-fetch-trace
istc-disable
dstc-disable
cpu-switch-time 1
load-module ruby
ruby0.setparam g_NUM_PROCESSORS 4
ruby0.init
con0.input "/usr/mark/a.out\n"
c

Did I perhaps misconfigure something that is causing a large slowdown?  Any
insight or advice would be greatly appreciated.

Thanks,
Mark