[Gems-users] a question about directory access

[Hui Zhao <hzhao5@xxxxxxxxx>]

Hi

   For those who understand the directory in memory/cache hierarchy, can you help me with this question?

I am running a simulation with MSI_MOSI_CMP_DIRECTORY protocol. From the trace I generate, when one address is missing in L1 cache, message is sent from

 L1 --> L2,

L2---> directory,

directory -->L2

L2-->L1.

 

This path seems like the directory acts as  a memory controller to get data from memory.

While my expected trace will be like

L1--->directory

directory-->L2

L2--->directory (or L1).

 

Can anyone explain why it is not like this?

 

Thanks