Re: [Gems-users] L2 cache miss actions

[Philip Garcia <pcgarcia@xxxxxxxx>]

Another fairly easy way to do this is to modify interfaces/ 
OpalInterface.C (assuming you're using opal, if not change the simics  
interface file).  The function advanceTime is called every cycle, so  
you an just put a hook in there that will call your function every X  
cycles (if you really want to have fun modify the files in the config  
directory to make this parameterizable at runtime).
Phil
On Jul 1, 2008, at 9:07 AM, Konstantinos Nikas wrote:

> Hi Mike,
>
> thanks for the suggestion. I managed to record the information I  
> wanted
> but now I am stuck at another point :-) .
>
> What I want to do is make Ruby call a specific method (which is  
> going to
> look into the L2 cache and do some tricks) every 1 million cycles.
> However I am not sure how I am supposed to do that, since (if I have
> understood it correctly) Ruby does not simulate every single cycle,  
> but
> instead wakes up whenever there is an event from the processor.
>
> Any suggestions?
>
> Kind regards,
>
> Kostis
> > Just add a field to the Entry structure (defined in L2cache.sm) and
> > then update the field with L2cacheMemory[addr].thread_ID :=
> > in_msg.Requestor or similar
> >
> > --Mike
> >
> >
> > On Thu, Jun 26, 2008 at 9:26 AM, Konstantinos Nikas
> > <knikas@xxxxxxxxxxxxxxxxx> wrote:
> >
> > > Hi all,
> > >
> > > I want to use Gems to study cache replacement policies for CMPs.  
> > > One of
> > > the things I need to do is add to the L2 cache a thread_ID field  
> > > which
> > > will hold the id of the processor/thread that brought the cache  
> > > block
> > > into the L2 cache in the first place.
> > >
> > > So, I have added an array that holds the id to the CacheMemory  
> > > class and
> > > whenever deallocate is called I reset the thread_ID of the touched  
> > > block
> > > (this is the easy part of course :-) ).  The problem is that I am  
> > > not
> > > sure how to set the ID whenever a new block is allocated into the  
> > > cache.
> > > First of all, I am not sure what happens when a L2 miss is  
> > > detected. I
> > > would assume that the following happens :
> > >
> > > L2 miss detected -> L2_cacheMemory.cacheProbe (to find the  
> > > replacement
> > > victim) -> L2_cacheMemory.deallocate (deallocate the selected  
> > > victim) ->
> > > L2)_cacheMemory.allocate (allocation of the new block).
> > >
> > > Is that right? And more importantly where is this sequence defined?
> > >
> > > I 've looked at the generated code of the protocol and I found  
> > > that in
> > > L2Cache_Transitions.C the qq_allocateL2CacheBlock method (which  
> > > calls
> > > the allocate method of CacheMemory) is called when for example the  
> > > state
> > > in L2 is NP (not present) and the event is  
> > > L2Cache_Event_L1_GET_INSTR.
> > > However I wasn't able to find where the victim cache block was  
> > > selected
> > > and deallocated prior to the new block's allocation.
> > >
> > > Any pointers/comments/insights will be greatly appreciated!
> > >
> > > Kind regards,
> > >
> > > Kostis
> > >
> > >
> > > _______________________________________________
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>
> --
> Dr. Konstantinos Nikas
> Computing Systems Laboratory
> School of Electrical and Computer Engineering
> National Technical University of Athens
>
> Tel: +30-210-7722495
> e-mail: knikas@xxxxxxxxxxxxxxxxx
> http://www.cslab.ece.ntua.gr/~knikas
>
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