Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!mcvax!kth!draken!d88-jwa
From: d88-jwa@nada.kth.se (Jon W{tte)
Newsgroups: comp.sys.mac
Subject: Re: RAM cache size
Message-ID: <1160@draken.nada.kth.se>
Date: 3 Jun 89 10:10:03 GMT
References: <4178@bgsuvax.uucp> <141200040@cdp> <1147@mtfmi.att.com>
Reply-To: h+@nada.kth.se (Jon W{tte)
Organization: Royal Institute of Technology, Stockholm, Sweden
Lines: 25

In article <1147@mtfmi.att.com> mec@mtfmi.UUCP (79153-M.CONNICK) writes:

>Somehow I doubt that Apple is using a serial search to access disk
>blocks in the cache! I'm sure they are using some type of hashing
>scheme.

Picking the TechNotes of the shelf reveals:
TechNote #81 page 2 of 3 line 36ff:
Up to 36 separate files may be buffered by the cache. Each queue is
a list of blocks cached for that file. Information is kept about the
age of each block, and the blocks are also kept in a list in the
order in which they occur in the file.

It also says that the least recently used blocks are the ones to go
when new blocks are read. It ALSO states that INIT 35 handles the
cache, through loading the caching CODE into the cache buffer in the
application heap, so you could write your own, hashing, code for
this, I suppose. But Apple Computer Inc (TM) stick to their sequential
lists, also used in the Resource Manager, List Manager, Dialog
Manager, Text Edit ... (Sorry about all the tech talk in this group)

-- 
 __       Jon W{tte (The dread Smiley Shark) email:h+@nada.kth.se
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