ejb@think (Erik Bailey) (05/31/91)
[hey! what ever happened to the line ea...]
I've got a few questions about System 7. I'm running it on a Mac IIsi
5/80, and so far so good (except for a few crash & burn situations where
not even Cmd-Opt-Esc could help [oh for a protected environment!] and the
slowness [esp TrueType - much slower than under 6.0.7]).
Here's what I'm wondering . . .
1) What kind of overhead does VM involve? That is, if I'm running an
application that would normally fit entirely in PHYSICAL memory, what
performance loss (if any) do I experience by using VM (I'm set up with
10M VM now, and it seems to be quite transparent)?
2) The same question for 32-bit addressing... Assuming an application
supports it and doesn't crash, is 32-bit slower/faster/the-same-as
24-bit? Is there any reason to use 32-bit addressing with the small
amount of memory I have?
3) Why won't the system use the pretty floppy disk icon when I'm in 8-bit
mode? It persists in using the 1-bit icon. Incidentally, for you IIsi
owners out there, I *highly* recommend the tip circulation about setting
the RAM cache to 768k -- it at least doubles video performance!
That's it for now. adTHANKSvance for any help! --Erik
--
Erik Bailey | 7 Oak Knoll | Thinking Machines Corp.
ejb@think.com | Arlington, MA 02174 | 245 First St.
harvard!think!ejb | (617) 643-0732 | Cambridge, MA 02142
/earth is 98% full. Please remove any excess inhabitants.jcocon@hubcap.clemson.edu (james c oconnor) (05/31/91)
[much deleted] > 3) Why won't the system use the pretty floppy disk icon when I'm in 8-bit > mode? It persists in using the 1-bit icon. Incidentally, for you IIsi > owners out there, I *highly* recommend the tip circulation about setting > the RAM cache to 768k -- it at least doubles video performance! Did Apple change the caching algorithm? If not, why the huge cache? I'd heard that the cache was pretty much a waste of RAM if it got over some small number, say 128k (remember when that was how much RAM Macs came with? I owned one of those). Inquiring minds want to know. Jim
ejb@think.com (Erik Bailey) (05/31/91)
In article <1991May31.155150.5074@hubcap.clemson.edu> jcocon@hubcap.clemson.edu (james c oconnor) writes: >[much deleted] > >> 3) Why won't the system use the pretty floppy disk icon when I'm in 8-bit >> mode? It persists in using the 1-bit icon. Incidentally, for you IIsi >> owners out there, I *highly* recommend the tip circulation about setting >> the RAM cache to 768k -- it at least doubles video performance! > >Did Apple change the caching algorithm? If not, why the huge cache? >I'd heard that the cache was pretty much a waste of RAM if it got over >some small number, say 128k (remember when that was how much RAM Macs >came with? I owned one of those). > >Inquiring minds want to know. > >Jim No, it actually has nothing to do with the disk cache at all! It's actually about the memory layout. NB -- this was NOT my idea, and I've lost the original post, so this is from memory (pun intended). Anyway, what happens is that the low (or is it high?) 1meg of memory is used for video ram. When small programs are loaded, they get loaded entirely or partly into this 1meg. For reasons I don't understand, this is VERY SLOW memory, possibly because of the frequent video access (?). Increasing the disk cache to 768k fills up the rest of the RAM (assuming you have built-in video set to 256 colors, which is 256k). I guess any technique that used up this memory in a productive way (eg RAMdisk) would also work. Important note -- I have noticed NO speed gain of the 768k cache as opposed to my old 256k cache in terms of DISK performance. This is purely a *video* enhancement. However, it makes 256-color mode fast enough that I leave my system there instead of in 16-color mode, since I like the pretty system 7 icons! :-) --Erik -- Erik Bailey | 7 Oak Knoll | Thinking Machines Corp. ejb@think.com | Arlington, MA 02174 | 245 First St. harvard!think!ejb | (617) 643-0732 | Cambridge, MA 02142 /earth is 98% full. Please remove any excess inhabitants.
lsr@Apple.COM (Larry Rosenstein) (06/01/91)
In article <1991May31.155150.5074@hubcap.clemson.edu> jcocon@hubcap.clemson.edu (james c oconnor) writes: >[much deleted] > >Did Apple change the caching algorithm? If not, why the huge cache? >I'd heard that the cache was pretty much a waste of RAM if it got over >some small number, say 128k (remember when that was how much RAM Macs I think System 7 does fix the caching algorithm. At least if you click the Use Defaults button the system often recommends larger caches (e.g., 512K on my 16Mb fx). -- Larry Rosenstein, Apple Computer, Inc. lsr@apple.com (or AppleLink: Rosenstein1)
keith@Apple.COM (Keith Rollin) (06/01/91)
In article <13787@goofy.Apple.COM> lsr@Apple.COM (Larry Rosenstein) writes: >In article <1991May31.155150.5074@hubcap.clemson.edu> jcocon@hubcap.clemson.edu (james c oconnor) writes: >>[much deleted] >> >>Did Apple change the caching algorithm? If not, why the huge cache? >>I'd heard that the cache was pretty much a waste of RAM if it got over >>some small number, say 128k (remember when that was how much RAM Macs > >I think System 7 does fix the caching algorithm. At least if you click the >Use Defaults button the system often recommends larger caches (e.g., 512K on >my 16Mb fx). Under system 6.0.x, when a file is closed, the cached blocks associated with that file are places on a free chain. This means that if files are opened and closed a lot (like MPW's header/interface files), they gain little benefit from the cache. Under System 7.0, when a file is re-opened, any cached blocks belonging to it are reclaimed from the free chain. -- ------------------------------------------------------------------------------ Keith Rollin --- Apple Computer, Inc. INTERNET: keith@apple.com UUCP: {decwrl, hoptoad, nsc, sun, amdahl}!apple!keith "But where the senses fail us, reason must step in." - Galileo
rmh@apple.com (Rick Holzgrafe) (06/01/91)
In article <1991May31.151901.10137@Think.COM> ejb@think (Erik Bailey) writes: > 2) The same question for 32-bit addressing... Assuming an application > supports it and doesn't crash, is 32-bit slower/faster/the-same-as > 24-bit? Is there any reason to use 32-bit addressing with the small > amount of memory I have? I don't think there's any significant speed difference. (If there's any difference at all, I'd bet the 32-bit mode is a noodge slower: some memory manager data has been moved elsewhere in 32-bit mode and may take an extra instruction or so to access. I use both modes on a IIfx and notice no difference at all.) There's no reason I know of to use 32-bit mode unless you need more than 8 Meg of memory (real or virtual.) ========================================================================== Rick Holzgrafe | {sun,voder,nsc,mtxinu,dual}!apple!rmh Software Engineer | AppleLink HOLZGRAFE1 rmh@apple.com Apple Computer, Inc. | "All opinions expressed are mine, and do 20525 Mariani Ave. MS: 3-PK | not necessarily represent those of my Cupertino, CA 95014 | employer, Apple Computer Inc."
Charlie.Mingo@p4218.f421.n109.z1.FidoNet.Org (Charlie Mingo) (06/01/91)
rmh@apple.com (Rick Holzgrafe) writes:
RH> There's no reason I know of to use 32-bit mode unless you need more than 8
RH> Meg of memory (real or virtual.)
You mean "more than 13 Meg of memory," right?
How do you get to 8 Meg from 24-bit (2^24 => 16 Meg - 3 Meg overhead =>
13 Meg)?
* Origin: "Each to his point of bliss" -- Browning (1:109/421.4218)rmh@apple.com (Rick Holzgrafe) (06/04/91)
In article <675796474.1@blkcat.FidoNet> Charlie.Mingo@p4218.f421.n109.z1.FidoNet.Org (Charlie Mingo) writes: > rmh@apple.com (Rick Holzgrafe) writes: > > RH> There's no reason I know of to use 32-bit mode unless you need more than 8 > RH> Meg of memory (real or virtual.) > > You mean "more than 13 Meg of memory," right? Bother - and I've been trying so hard to get everybody straight on this. Yes, you're (nearly) right. With Virtual Memory turned on, the maximum memory is (14 - (number of NuBus cards)) Megs. (You can get 14 Meg if your Mac has on-board video, though of course some of that gets used by the video.) With VM turned off, the max is 8 Meg for Mac II family machines. ========================================================================== Rick Holzgrafe | {sun,voder,nsc,mtxinu,dual}!apple!rmh Software Engineer | AppleLink HOLZGRAFE1 rmh@apple.com Apple Computer, Inc. | "All opinions expressed are mine, and do 20525 Mariani Ave. MS: 3-PK | not necessarily represent those of my Cupertino, CA 95014 | employer, Apple Computer Inc."