[G4] RAM Advisory

[Joseph B. Gurman]

     Lavode wrote:

>OK, I know that more RAM is good.  However, I also know that there 
>is a point of diminishing returns.  I have 600+ mb in my PowerMac 
>7300 running OS 8.6, and it could just as well have 400 mb and it 
>would still work just as well.
>
>I also have a Yikes with 300mb RAM running 10.2.8.  The question is, 
>will I get a noticeable increase in performance by adding more RAM? 
>Not knowing how much of a memory hog X is, I don't want to add RAM 
>when it won't do me much good.  I don't render, and don't have a lot 
>of memory intensive applications.

     On a MDD dual 1.0 GHz G4, I'm (as I write) running Eudora 6, 
Terminal (one window, to run top [see below]), Safari, Vicomsoft's 
Internet Gateway, iCal, Word, and a couple of startup apps (e.g. 
Default Folder X). According to the command-line app top, 659 Mbyte 
of the 1.25 Gbyte of memory installed is in use. I sometimes run much 
more memory-intensive stuff (large Photoshop files, scientific 
computing/display), so the > 1 Gbyte is not a luxury.

     What more memory gives you is one of the key features of OS X (or 
any true multitasking OS): the ability to run lots of stuff at the 
same time, fast. The San Jose Mercury News had a recent article,

	http://www.bayarea.com/mld/mercurynews/business/6970136.htm ,

about the G5 that reported how they were able to up-res a ~ 100 Mbyte 
Photoshop image to 1.6 Gbyte in three minutes at the same time they 
were ripping a CD in iTunes and watching a DVD at full-screen res. 
CPU speed, multithreading, look-ahead, datapath width, &c. all help, 
but they couldn't have done it without a lot of physical memory. 
Absent that, and the system starts wasting gobs of time using the 
hard drives for virtual memory.

     So the answer to, "How much is enough?" depends critically on 
what you do with the machine.

     Your mileage will certainly vary,

						Joe Gurman
-- 
"I love deadlines. I love the whooshing sound they make as they go by."
                                                             - Douglas 
Adams, 1952 - 2001

Joseph B. Gurman, NASA Goddard Space Flight Center, Solar Physics
Branch, Greenbelt MD 20771 USA