Author: Sune Fischer
Date: 15:14:15 08/25/03
Go up one level in this thread
>(status quo). Right, saw that one too late :) >That is exactly what I said. The issue is how many copy/makes have to be >done per unit of time. Or how many units of time it takes to do a single >copy/make. Depends on your time scale (1s or 1ns). > >A single cpu that will run crafty at 1M nps has a cache-cache and cache-memory >bandwidth of X bytes/second. A single cpu that runs crafty at 2M nps has >exactly twice the cache-cache and cache-memory bandwidth and twice the clock >frequency. A dual-cpu just needs two cpus, but the two cpus give twice the >cache-cache bandwidth, but _no_ improvement in cache-memory bandwidth. > >This was all about memory bandwidth with respect to copy/make. Aaah, and here lies our source of disagreement. I was always talking about cache to cache, or as Johan wrote "C2C" bandwidth. I think the assumptions for make/uncopy to match make/umake is that the stack fits in cache, or else it will be heavily outgunned, even on a single. I doubt anyone disagrees with you there. >> >>You made it sound like 2.4 was much worse than 1, which is just a silly >>comparison at best. > >Clearly 2.4 _is_ much worse than 1. It requires 2.4X the bandwidth. Yes _if_ you need to go over the bus. -S.
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