Re: [Gems-users] Question about warm application in Simics

[Liping Xue <lxue@xxxxxxxxxxx>]

Liping,

Liping Xue wrote:

> > Hi, I have a question about warm application in Simics.
> > In the ISCA tutorial about gems, they use "Barnes" as a example.
> > It said that to warm up application in Simics, in the console window, using
> > --------------------------------------------------------------------------------------
> > *./BARNES < input-warm*
> > After this, write checkpoint "barnes-cold-16p.check"
> > and they use the second run to warm up cache:
> > the command is:
> > *./BARNES < input-run >output; magic_call break
> > --------------------------------------------------------------------------------------------------------
> >
> > *I have several questions about the above procedure:
> > 1. What is the difference between parameter "input-warm" and 
> > "input-run"? Can I use a small size of "input-warm" and a big size of 
> > "input-output"?
>  
That is OK. You can use a small input set for "input-warm" and the big 
input for "input-run". You just need to have memories/caches warmed up 
to avoid cold start misses.

> > 2. What is the meaning of "magic_call break", I typed it in the console 
> > window, but it says that "command not found".
>  
You should consult the Simics manual on how to use magic break points. 
You would like to have a binary (maybe in /bin) that calls the Simics 
magic break function. Alternatively, you can add a magic break call (and 
include the corresponding .h file) in your source code and recompile.

> > 3. What's the purpose of "warm-checkpoint"? How to get a 
> > "warm-checkpoint"? (I know in the slides it give the example to use the 
> > "go.simics" script, but when I use it, it gives me so many errors).
>  
The warm checkpoint should have warmed up caches. After you run for the 
warmup interval, you should save cache data using something like:
ruby0.save-caches CHECKPOINT_NAME.caches.gz

(in addition to saving the checkpoint using the simics command 
"write-configuration"
Then when you load your checkpoint for your real run, you should have 
ruby warm up caches using:
ruby0.load-caches CHECKPOINT_NAME.caches.gz

And then proceed to clear ruby stats and start the simulation.

I hope that helps.

-Alaa


Hi, Alaa,
 Thanks for your replay, it really helpful. But I am still have some questions.
The following is my understanding of your reply, please correct me if I made a mistake.
For each application, we need "three runs".
1) first run  (Only need Simics to simulation)
----------------------------------------------------------------------------------------
 * The Console command: ./BARNES < input-warm *
  write-configuration CHKPT_DIR/barnes-cold-16p.check  (generate cold checkpoint)
-----------------------------------------------------------------------------------------

2) second run  (Need Simics+Ruby)
-------------------------------------------------------------------------------------------
load "cold" checkpoint generated in the first run,
set up ruby
  *The Console command: ./BARNES < input-warm *

  ruby0.save-caches barnes.caches.gz  (generate warmup cache file)
   write-configuration CHKPT_DIR/barnes-warm-16p.check (generate warm checkpoint)
----------------------------------------------------------------------------------------------
3) third run (Real simulation)
----------------------------------------------------------------------------------------------
load barnes-warm-16p.check
load barnes.cache.gz
clear ruby stats
start simulcation
*The Console Commands:./BARNES < input-run > output; magic_call break
*------------------------------------------------------------------------------------------------

For the above process, why we need "magic_call break" only in the third run. What is the purpose of this
command? I can not find a executable named "magic_call" in my machine. But I find a file named "magic_call.c" in
~/ruby/simics. It is seems a file provided by Ruby designer.

Thanks for your help!

-- Liping