Re: [Gems-users] "e_sendData" in MOESI_CMP_directory-L1cache.sm

[Marco Solinas <marco.solinas@xxxxxxxxxxxx>]

I've never worked with this protocol, but in my view (please correct me 
if I'm wrong) it is correct because the request is a GETS, so a 
non-exclusive read. The cache receiving the block will store it in the S 
state, (transition(IS, Data, S){...}), so the block has not to be 
considered dirty for the requesting node; instead, the dirty information 
is still held by the sender cache, that changes the state from M to O. 
In fact, when the Ownership changes (in case of a GETX forwarded to a 
cache that holds a block in either M or O), the action used to provide 
the requesting cache with the block is not e_sendData, instead it is 
e_sendDataExclusive (transition(M, Fwd_GETX, I){...} and transition(O, 
Fwd_GETX, I){...} for example). This action set the Dirty flag of the 
outgoing message to the same value of the Dirty flag of the cache tag.
Marco

Hui Li ha scritto:
> hello,
> the action e_sendData in MOESI_CMP_directory-L1cache.sm always does this:
>   out_msg.Dirty := false;
> so it means that the contents in the cache entry are the same with memory.
> however, in transition:
>   transition(M, Fwd_GETS, O) {
>     e_sendData;
>     l_popForwardQueue;
>   }
> the Dirty flag should be true, right? or I missed some point?
> regards,
> lihui
>
>
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