Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!decwrl!ucbvax!bloom-beacon!think!ephraim
From: ephraim@think.COM (Ephraim Vishniac)
Newsgroups: comp.sys.mac
Subject: Re: Mac II I/O rates vs. block size
Message-ID: <39756@think.UUCP>
Date: 27 Apr 89 13:33:18 GMT
References: <39736@think.UUCP> <8904270059.AA02169@vs08csc.UMD.EDU>
Sender: news@think.UUCP
Reply-To: ephraim@think.com (Ephraim Vishniac)
Organization: Thinking Machines Corporation, Cambridge MA, USA
Lines: 40

In article <8904270059.AA02169@vs08csc.UMD.EDU> russotto@wam.UMD.EDU writes:
>In article <39736@think.UUCP> ephraim@think.COM (Ephraim Vishniac) writes:
>>Several months ago, Ed Darken reported that he'd written a simple
>>program to check the Mac's I/O speed and found it execrable,
>>independent of I/O block size.

>>Guessing that FSWrite was doing a series of single-sector writes, I
>>modified Ed's program to use PBWrite instead, and I got the following
>>results:

	[Output rates increasing sub-linearly with block size]

>>Plainly, FSWrite has serious brain damage.

That should be, "Plainly, FSWrite *had* serious brain damage."

>Since FSWrite is development-system-dependant, could you please
>tell us which development system was used?

Ed originally wrote his program in MPW C (before MPW 3.0, so probably
with 2.?) and also ported it to LSC 2.??.  I'm now running with LSC
3.01p4.

I should have finished doing my homework before posting my results, as
it seems that the problem Ed originally observed is gone from LSC
3.01p4.  That is, I went back to the original program, ran it again,
and got results just like those from using PBWrite.  So, using FSWrite
is actually a non-problem if you're using an up-to-date version of
LSC.

BTW, I also nosied both versions of Ed's program (with FSWrite and
with PBWrite) and confirmed that both are effectively calls to _Write.
Unfortunately, I didn't have an old version around to see if FSWrite
had changed.

Ephraim Vishniac  /  Internet: ephraim@think.com  / AppleLink: ThinkingCorp
Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142-1214

	"Arlo Guthrie, it seems, has found what he was looking for:
		God, and the Macintosh." (Boston Globe)