Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!newstop!sun!coherent!dplatt
From: dplatt@coherent.com (Dave Platt)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Inits & Boot Time
Keywords: INIT
Message-ID: <29712@coherent.com>
Date: 31 Jul 89 17:27:03 GMT
References: <1179@snjsn1.SJ.ATE.SLB.COM> <4101@lindy.Stanford.EDU>
Reply-To: dplatt@coherent.com (Dave Platt)
Organization: Coherent Thought Inc., Palo Alto CA
Lines: 54

In article <1179@snjsn1.SJ.ATE.SLB.COM> enk@sj.ate.slb.com (Edan Kabatchnik) writes:
>     1) Does the bottleneck arise from the actual loading of the INITs or
>        the seek time in between INITs?  (Of course, this may vary from
>        machine to machine depending on processor, hard disk, etc.)

Disk performance has a great deal to do with it.  In fact, performance
can vary greatly even on a single model of disk, depending on the
efficiency of the disk driver.  The following anecdote illustrates this
point.

I have a Mac II and a Micah AT-100 drive... the Micah uses a Rodime
100-meg (5000S series) mechanism (access time ~~ 28 msec typical).

I used the Micah-supplied driver for 6-8 months... performance was good,
and the system booted quite nicely.  After System 6.0 came out, I
discovered that the Micah driver was vulnerable to a bug that Apple had
introduced in System 6.0;  the drive could not be formatted, or verified
via Disk First Aid.

I switched over to another driver-package that the folks at Micah sent
me... I believe it was a member of the driver-family written and
marketed by Software Architects.  It was compatible with System 6.0, and
could partition my 100-meg disk into several subvolumes (something that
the Micah driver for the Mac II could not do).  But WOW, was it slow!
Booting the machine and running my collection of INITs took almost twice
as long as under the Micah driver.  The drive seemed to spend lots of
time with its "busy" light on, but wasn't getting nearly as much work
done as before.  The whole system had a more sluggish feel to it.

A couple of months later, I received a copy of the latest version of
Rodime's disk-driver software from Rodime's tech-support group...
compatible with 6.0, and capable of partitioning a Rodime disk.  I
backed up my disk, reformatted using the Rodime utility, and restored
the files.

Lo and behold, the disk's performance was back up in the same ballpark
as before... the INIT-icons popped up one after another, with no
agonizing pause between them.  The system's overall "feel" was no longer
painfully sluggish.  I _think_ that the Micah driver may have been a
hair faster than the Rodime driver... but both the Micah and Rodime
drivers were far and away more efficient than the Software Architects
driver.

I suspect that the SA driver may have been making lots of small
(single-block) transfer requests, while the Micah and Rodime drivers
were able to make larger requests (possibly with some sort of in-memory
cache in the driver itself).


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