Re: [Gems-users] Questions about MOESI_CMP_directory

[Mike Marty <mikem@xxxxxxxxxxx>]

> We are studying the MOESI_CMP_directory and we have
> some questions about it.
>
> Why must the L1 send the data to the L2 if it's not
> modified when it makes a replacement from Shared
> state?
>

It may or may not send the data from the S state.  The L1 sends a PUTS
message to the L2 cache.  If the L2 does *not* have the data, then it
replies with a message saying "send me the data".  Otherwise it tells the
L1 to drop the data.  Recall that the L2 is non-inclusive with the L1
caches.  Thus the L1 sharer may hold the only copy of the data on-chip.

> Which functionallity does the action uu_profileMiss
> have in the  L2?
>

It supposed to profile misses.  It may not be hooked up right.

> Why does the L2 consider local and non local L1 caches
> and has different states for them?
>

I'm not sure what you  mean.  You can refer to a particular place?


> Why does the L2 need a PerfectCacheMemory?
>

This holds the L2 directory state and approximates L1 shadow tags.

--Mike