 |
|
|
 |
||
|
||
|
||
|
|
Quicklinks: · Power Macs · 'Books · Early Macs · Week's Best Deals · Best Buys · OS Downloads |
|
RAM Disk or Disk Cache?Low End Mac Reader SpecialsMemory To Go Special: MacPro 8 Core Memory 4GB kit $154 / 2GB kit $94, New 2008 iMac 2GB $46. MacBook Pro / MacMini / iMac Intel Core2 DUO 2GB $44 / 1GB $23--Free shipping available. Download Typestyler, still the Ultimate Styling Tool for Internet, Print and Video Graphics. Works great in Classic with a Native OS X Version on the way. Free Tryout: www.typestyler.com
OWC: Top Quality Memory for Faster Mac Performance 1GB/2GB/4GB Kits from $23.99/$47.99/$94.99 Expert Support, Free Installation Videos & Guides, Lifetime Advance Replacement Warranty - www.MacSales.com Mac users can finally play Party Poker for Mac. Not only that, they can also learn how to play PokerStars for Mac.
Compare products like desktop computers, laptops, and LCD TVs side by side! All the information and reviews to make the best purchasing decision for a new cell phone GPS products or MP3 players. The Ciao network makes searching products easy for you.
Scott L. Barber Scott L. Barber first posted this to Quadlist. It is reprinted with his permission. I want to rattle on about this, since Dan is testing out some of the things I've postulated about before. I keep seeing this dual RAM Disk/Disk Cache trend, and it astonishes me. I just haven't figured out why everyone wants to equate them together, and then it dawned on me - some people are using their RAM disk as their Netscape cache folder. So, armed with this obscene information, I'm gonna make some comments . . . read on. . . .
I very much like the "With Speedometer" part of this phrase. That's a very crucial part of the sentence. Performance increases level off at 2 MB with MacBench on almost every machine, but neither MacBench nor Speedometer test normal use, they only test their own patterns. This is the difference between real world and lab world use.
When the RAM disk is accessed, performance for those cached items from the RAM disk are exactly 50% slower because of dual checking, checking the cache and then the RAM disk. Performance drops from this point are due to latency and bus utilization. Speed Doubler fixes this by using an optimized cache routine, and I think even tells the disk cache to ignore RAM disks - but I'm not sure on the latter.
This really depends on why you're using a RAM disk. If you're using a RAM disk for Netscape, just can the RAM disk and raise you're cache - this eliminates the above "memory mirroring" effect. A long time ago, people started this Netscape RAM disk thing, and it's easier to just increase your disk cache by the same amount as you'd dedicated to a RAM Disk, to get the performance boost. OK . . . it's a little slower than using a RAM disk because of the SCSI checks, but again, Speed Doubler helps this a lot, and it also helps out other programs other than Netscape, and the system software as well, which can mostly be held in cache memory . . .
Bingo - you have an excellent grasp of how the block transfer issue affects disk cache on SCSI hard drives. There's almost a harmonic effect about it . . . Now . . . for the notes. And I have published all these before on the list . . . The only clients that I have ever recommended a dedicated RAM disk
to are the consistent Photoshop users, and they're told to turn their
Primary Scratch Disk to this 4 MB RAM disk. This is designed to cache,
through Adobe's unique built in VM caching routine, the first 4 MB of
their VM cache, which contains all of the cache headers, the filter
information, and all of the programing hooks that are always sent to
the hard drive, no matter how much memory you allocated to Photoshop.
Quadlist, the listserv for users of 68040-based Macs. FAQ at <http://lowendmac.com/lists/quadlist.shtml> Related articlesRecent Online Tech Journal Columns
Recent Content on Low End Mac
|
Have a question?
|
