Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!usc!apple!marc
From: marc@Apple.COM (Mark Dawson)
Newsgroups: comp.sys.mac.system
Subject: Re: RAM Cache
Keywords: best size
Message-ID: <41707@apple.Apple.COM>
Date: 7 Jun 90 16:41:52 GMT
References: <41628@apple.Apple.COM> <732@usage.csd.unsw.oz.au> <41579@apple.Apple.COM> <1990Jun5.174114.7515@Neon.Stanford.EDU> <41664@apple.Apple.COM>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 41

In article <41664@apple.Apple.COM> marc@Apple.COM (Mark Dawson) writes:
>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
>
I meant 512 byte blocks + a compile (MPW) does a lot of writes.  A larger
RAM cache may still improve performance if you're doing more reads.  Thanks
to those who pointed out my typos.
Mark



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

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