Path: utzoo!attcan!uunet!husc6!cmcl2!rocky8!cucard!ccnysci!alexis
From: alexis@ccnysci.UUCP (Alexis Rosen)
Newsgroups: comp.sys.mac
Subject: Re: Reeks on Disktimer (LONG)
Message-ID: <983@ccnysci.UUCP>
Date: 12 Nov 88 08:34:15 GMT
References: <698@mouse.UUCP>
Reply-To: alexis@ccnysci.UUCP (Alexis Rosen)
Lines: 47

I would really like to see some hard information come out of this little flame
war. Right now, we have very little. The Reeks article was a fair start,
and now if Ephraim cares to answer it we'll really be getting somewhere. I
would like to point out one thing, though- While I'm not expert on this
subject, there are some things I do know:

In article <698@mouse.UUCP> lad@mouse.UUCP (Larry Deleski) writes:
>I would like to take this opportunity to point out an error in something I
>said earlier.  I stated that Disktimer did not use the Device Manager.  It
>does,  but not in the same way a typical SCSI driver does.  What Disktimer 
>fails to do is use the FileManager,  something every driver has to do.
>
>Please read the following and decide for yourself.  Reekes *does* know 
>what he's talking about.

But Larry apparently does not. To quote from the Reeks article which he
appended to this same posting:
>[Disk requests go through this chain:]
>Application>>FileManager>>DeviceManager>>DeviceDriver>>SCSIManager>>
>HDController>>HardDisk

So drivers NEVER use the File Manager; it uses them. In fact the entire
paragraph seems garbled. Larry might be trying to say that DiskTimer II never
uses the File Manager, whereas normal programs always do. If that's true, it
sounds like a valid criticism. Regardless of the merits of this argument,
Larry is not demonstarting the kind of expertese that makes me want to trust
his judgement on this matter.

One other point- while the Reeks article sounds fairly expert, there are a
few major oddities that stand out. At one point he says the seek time of the
drive he's discusing is 65 ms, and thus should always yield the same seek
numbers. The 'seek time' is really an average time, which bears only vauge
resemblance to any individual seek. (It is is true that the same seek should
take the same amount of time, not counting rotational latency.) Whether this
invalidates his point depends on whether DiskTimer always seeks between the
same exact tracks each time it is run on any one disk.

Now, would the real expert please stand up?

p.s. Please don't construe any of this as a personal attack of either Larry or
     Jim Reeks. I'll leave that to others :-)  Flames to /dev/null.

----
Alexis Rosen                       alexis@dasys1.UUCP  or  alexis@ccnysci.UUCP
Writing from                       {allegra,philabs,cmcl2}!phri\
The Big Electric Cat                                       uunet!dasys1!alexis
Public UNIX                           {portal,well,sun}!hoptoad/