Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!bu.edu!snorkelwacker!apple!marc
From: marc@Apple.COM (Mark Dawson)
Newsgroups: comp.sys.mac.system
Subject: Re: RAM Cache
Keywords: best size
Message-ID: <41664@apple.Apple.COM>
Date: 6 Jun 90 14:40:55 GMT
References: <41628@apple.Apple.COM> <732@usage.csd.unsw.oz.au> <41579@apple.Apple.COM> <1990Jun5.174114.7515@Neon.Stanford.EDU>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 35

In article <1990Jun5.174114.7515@Neon.Stanford.EDU> philip@pescadero.stanford.edu writes:
>In article <41628@apple.Apple.COM>, marc@Apple.COM (Mark Dawson) writes:
>> To give you an example, to compile, link, and Res (via MPW 3.1) my MacApp 
>> program (on a IIfx), it took 2 HOURS with RAM cache OFF and 20 MINUTES with
>> a 1 or 1.5 meg RAM cache.  Note that increasing the cache 512K from 1meg 
>> didn't improve the speed any (I'm still investegating what the speed cutoff
>> is).
>Isn't this perhaps an indication that the traditional compile/link/run/crash
>cycle ought to be re-evaluated? It's hard to discuss alternatives without
>being accused of starting arguments about "my compiler is better than yours",
>but I've often felt the "integrated environment vs powerful tools" argument
>misses the point. RAM is relatively cheap, and designing a whole development
>system around the premise that it's cheaper to pipe multiple passes through
>the file system than to store everything in RAM as far as possible is 1970s
>thinking. So is there a better way? I can't believe using a large RAM cache
>is the only solution to a performance problem that has at its heart the
>overall architecture of the program being run.
>
A follow up note: I further reduced my RAM cache from 1meg to 96K and the
compile/link time went down to 16 minutes.  I've since been told that they
way the Mac ram cache is implemented makes it counter-productive to have large
caches, since it writes out the cache in 512K blocks (so a large cache will
require many writes).

Mark



-- 
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Mark Dawson                Service Diagnostic Engineering
AppleLink: Dawson.M

Apple says what it says; I say what I say.  We're different
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