[Gems-users] Question about MOESI-CMP-directory

[Hamid Reza Khaleghzadeh <khaleghzadeh@xxxxxxxxx>]

Hello

I have simulated a 8 cores CMP where consists of 4 chips and each chip 
has 2 cores and one shared L2. MOESI-CMP-directory is coherency 
protocol.

Core0    Core1     Core2    Core3     Core4      Core5       Core6      Core7
   |------------|             |------------|            |---------------|              |---------------|
          |                         |                          |                               |

         L2 __ Dir0           L2 __ Dir1            L2 __ Dir2                 L2 __ Dir3
          |-------------------------|--------------------------|-------------------------------|

                                                   |
                                               Memory

Consider described architecture. Suppose only DL1 of Core2 has data X. At this point, Core3 (Cores 2 and 3 belong to same ship and have a shared L2) requests X. There are two approaches for responding to this request:
1- Directory set state of X to SHARE and then read data from L2.
2- Without any access to directory, data read from L2 and state of X doesn't change.

I think 2 is correct. Could you help me?