Mailing Lists: Apple Mailing Lists
Image of Mac OS face in stamp
 
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: McDougall's Disk Masher (was: Mac OS X File IO Performance Issue?)

I think all other things being equal it might make a reasonable basis for comparison. But you would need to be very careful that all other things were in fact equal. For one thing it seems to degrade reasonably quickly if anything else is going on.

This is a Mac Mini,  1.42GHZ G4 512MB 80G. 

First run I was playing  X11 gnuchess at the same time, unfortunately lost on a sort of nifty back rank mate. You wouldn't think real I/O bound anyways.

FileOutputStream write 8M (avg)   161
FileInputStream read 8M (avg)  196.
FileOutputStream fill and write 8K avg   215
FileInputStream read and check 8K avg  475
Time: 56.044

Tried some subsequent tests without anything I knew of going on...
FileOutputStream write 8M (avg)               113 - 82   - 80
FileInputStream read 8M (avg)                  135 - 160 - 164
FileOutputStream fill and write 8K avg     130 - 115 - 189
FileInputStream read and check 8K avg  286 - 291 - 308
Time: 34.484 - 37.426 - 38.552

Hmm, better all the way around. Last one pretty poor for some reason unknown to me. Let's try one where one where we fire up Safari at the same  time and do a little browsing...
FileOutputStream write 8M (avg)   309
FileInputStream read 8M (avg)  156
FileOutputStream fill and write 8K avg   160
FileInputStream read and check 8K avg  267
Time: 47.213

The initial launch seemed to hit heavy on the write time and have only so-so, if any, impact on subsequent results. But this still slowed total time a fair amount. So you would I think need to stress that testing should take place on an idle machine, or carefully compare it against the same other stuff going on. 
Or, you are going to get results where to a large extent it depends on what else might be going on?

(usually attributed to Mark Twain or Benjamin Disraeli): "There are three kinds of lies: lies, damned lies, and statistics."

I always thought that was Disraeli but googling seems to show that even that is subject to speculation.
 _______________________________________________
Do not post admin requests to the list. They will be ignored.
Java-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/java-dev/email@hidden

This email sent to email@hidden
References: 
 >McDougall's Disk Masher (was: Mac OS X File IO Performance Issue?) (From: Craig Mattocks <email@hidden>)



Visit the Apple Store online or at retail locations.
1-800-MY-APPLE

Contact Apple | Terms of Use | Privacy Policy

Copyright © 2007 Apple Inc. All rights reserved.