Re: [Gems-users] Invalidate directory entry

[Mike Marty <mikem@xxxxxxxxxxx>]

This protocol stores the directory state in the L2 cache tag.  The
L2_Replacement will eventually cause the L2 controller to deallocate the
L2 cache tag.  When both the TBE (for handling the replacement of shared
or dirty data) and the L2 tag is deallocated, then the Directory state is
gone and considered NP (Not Present), equivalent to I.

For example, replacing M will deallocate L2 tag immediately but allocate a
TBE (to handle the demand miss causing the replacement in parallel).
Eventually this transition occurs, which will actually result in state NP
(Not Present) even though the target transition state is L2_I.  If there
is nothing to hold the state L2_I, then the state is L2_NP

  transition(L2_MIN, Dir_WB_ack, L2_I) {
    s_deallocateTBE;
    l_popForwardedRequestQueue;
  }


That was a confusing explanation.

--Mike


 > Hi list, >
> I'm looking at MSI_MOSI_CMP_directory-L2cache.sm file and I'm wondering after a L2_Replacement, where/how did the protocol change the state of the corresponding directory entry to invalidate that? Please advise.
>
> Thanks,
> Lei