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View Full Version : more memory = faster OS X performance?



jfruh
07-09-2001, 10:13 PM
hi there all-

I'm using a dual processor 450 MHz G4 w/128 MB of RAM running OS X. When I got the machine a year ago, it seemed to hum along (especially compared to my old 145 MHz Power Computing machine!) but OS X is noticeably -- sometimes maddeningly -- sluggish. Most of the times when I am forced to wait for the OS to work, I can hear the disk churning, which leads me to believe that more RAM could help.


I know that I'm now at the minimum recommended amount of memory for my OS; I also remember that, when I upgraded my old machine from 16 MB to 80 MB of RAM, I was stunned by the performance boost. RAM seems to be pretty cheap right now, and ridiculously easy to install in the case of my machine, so I am serious considering getting an extra 256 MB. I do want to ask, though, before making that investment: does OS X performance improve w/more memory? Or do its speed problems lie elsewhere?

Thanks in advance,
Josh

ChrisYip
07-09-2001, 11:54 PM
I would have to say 'yes' to the more RAM is better theory...It makes a lot of sense to do the upgrade esp since prices are so low. There are also some other upgrades / fixed you can do to make it a bit faster - I think there are some posted to XLR8YOURMAC - some include the usual, faster drive, defragmentation etc...

Chris

jfruh
07-11-2001, 02:36 AM
A reply to my own post -- yes, I installed the memory, and yes the boost in performance was incredible! I've been working on the machine almost continuously since I installed the RAM 12 hours ago and have barely heard the hard drive churn at all; after months of hearing that constant grind, it's almost eerily quiet!

I also recommend the Mac Guru logic board diagrams -- guided an idiot like me right to the right place.

jf

ChrisYip
07-11-2001, 07:48 AM
Excellent - glad to hear it's working out so well...
Sounds like you had a lot of stuff going to your disk cache in the past and it's now all going to RAM.

Chris

chatwood2
07-11-2001, 09:10 AM
Glad to hear that the RAM increase helped. There is another option if you have a strong heart. OS X uses an 80+ MB file buried in the system folders as a swapfile (a sratch disk) for storing system settings, aqua layer data, etc. There is a hack that puts the swap file on its own partition, this speeds up performace a lot. If you have only one disk there still is a speed boot, but it help a whole lot more if you have 2 (1 for OS and files, 1 for swap partition and other files). The link to the hack is http://www.ResExcellence.com/hack_html_01/06-01-01.shtml . I warn you that a mistake in following directions could require reinstalling the OS, so be careful. Also, I have yet to try this out (i'm waiting for better SCSI support in X before I transition) so I don't know exactly how much boost you will get.

- Chris

drjoe
08-12-2001, 08:14 PM
JUst a few points. OS X will use ALL of the ram that you give it. It reserves a small amount for local catching but the great majority of the ram installed is used. I recently took a 233 Rev A beige DT from 233/192 to 466[XLR8]/640 and the perceived perfomanmce hike is very marked. As to swap files; OS X uses virtual memory is 80 meg 'chunks'. In the finder under 'GO' type in /var/vm. This takes you to the location of the virtual memory swap files. At startup OS X creates, by default, the first of these files [0]. Then as physical memory is used up it creates additional 80 MB files. Initially, with 192 MB the total swap space would creep up to 5*80 Mb and the system would be so slow as to require a restart. Also run 'top' in the terminal app and look at the very end of the display before the list of processes. What you want to look at is the number of 'pageouts' These are the number of times that information is paged from memory to disk. 0 is the best, less is better. Originally I had up to four or five VM files and 10-15% pageouts. With the 640 Megs - VM is not used and there are no pageouts. As to using a location for the backing store different from the OS itself obviously f you have enough physical ram and don't pageout info to disk it really doesn't matter where it is. Many UNIXES and LINUX distros use separate locations for swap files but I doubt, with enough ram it matters much.

drjoe

tm311
08-12-2001, 08:35 PM
How does OSX handle multiple posts???he-he