Re: [Gems-users] L2 cache miss actions

["Mike Marty" <mike.marty@xxxxxxxxx>]

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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