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Directory and memory parameters

memorylatency
This number specifies the DRAM access latency in cycles. (Note that this is only the actual time at the DRAM, and does not include time on the bus, in the caches, or at any other resource.) Defaults to 18 cycles (60 ns with a 300 MHz processor).

dircycle
This number gives the minimum directory access latency, which is the latency incurred by non-data responses to the directory. (Requests to the directory for data or data-carrying responses to the directory must access the DRAM and thus incur the latency specified by memorylatency.) This parameter is specified in processor cycles, and defaults to 3.

meminterleaving
This number specifies the degree of memory and directory interleaving at each node. Defaults to 4.

dirbufsize
This number sets the maximum number of pending requests at the directory at any time. If additional requests are received, they are bounced back to the sender with a retry request.

dirpacketcreate
Some transactions require the directory to send coherence requests to the other caches (such as invalidations or cache-to-cache transfer requests). This number specifies the time to produce the first such coherence request for a given transaction, in processor cycles. Defaults to 12.

dirpacketcreateaddtl
This number specifies the additional delay in processor cycles for each subsequent coherence request for a given transaction (after the first one). Defaults to 6.



Vijay Sadananda Pai
Thu Aug 7 14:18:56 CDT 1997