Re: Are 64 Int or FP registers useful?

pardo@cs.washington.edu (David Keppel)
Thu, 17 Sep 1992 20:32:05 GMT

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Related articles
Re: Are 64 Int or FP registers useful? hrubin@pop.stat.purdue.edu (1992-09-14)
Re: Are 64 Int or FP registers useful? preston@helena.cs.rice.edu (1992-09-16)
Re: Are 64 Int or FP registers useful? hrubin@pop.stat.purdue.edu (1992-09-17)
Re: Are 64 Int or FP registers useful? daveg@synaptics.com (Dave Gillespie) (1992-09-17)
Re: Are 64 Int or FP registers useful? pardo@cs.washington.edu (1992-09-17)
Re: Are 64 Int or FP registers useful? lfm@pgroup.com (1992-09-19)
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Newsgroups: comp.arch,comp.lang.misc,comp.compilers
From: pardo@cs.washington.edu (David Keppel)
Organization: Computer Science & Engineering, U. of Washington, Seattle
Date: Thu, 17 Sep 1992 20:32:05 GMT
Followup-To: comp.arch
References: <1992Sep7.091904.2626@newsroom.bsc.no> 92-09-099
Keywords: registers, optimize

hrubin@pop.stat.purdue.edu (Herman Rubin) writes:
>[Why even have separate int and fp registers?]


Because combining them slows the cycle time of the processor and the
designers are trying to maximize the weighted speed, namely the frequency
of occurance over all programs of each operation times the cost of that
operation. For any given workload a workload-specific design is always
better, but the speed over all workloads is worse.


As workloads change and and our understanding of them changes, processor
designs are optmized to those different workloads. The pessimizaton of
atypical workloads increases also.


Followups on this thread to `comp.arch'.


;-D on ( A minimum of registers ) Pardo
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