ralphw@ius3.ius.cs.cmu.edu (Ralph Hyre) (10/20/88)
In article <3924@encore.UUCP> bzs@xenna (Barry Shein) writes: >>Does Mach (on a NeXT, at any rate) do memory swapping to disk? >>If so, what does it use for the swap area at times when the laser disk is out? >I'll stick my neck out and say that I don't believe that you'll be >able to remove the optical disk if that's what you're paging and >swapping to That would be my guess, but CMU-CS flavored Mach kernels (supported by our excellent facilities staff here) have a nifty resource-pausing feature that will block selected processes that can't get at needed resources (like, free disk blocks when the disk is full). This has been in CMU-CS kernels since the BSD 4.1 days, I believe. It might be tough to extend this to paging and swapping, but if anyone can do it, NeXT can. I don't know if that what set of sources NeXT started with, though. disclaimer: I am no authority on how CMU and NeXT interact. -- - Ralph W. Hyre, Jr. Internet: ralphw@ius3.cs.cmu.edu Phone:(412) CMU-BUGS Amateur Packet Radio: N3FGW@W2XO, or c/o W3VC, CMU Radio Club, Pittsburgh, PA "You can do what you want with my computer, but leave me alone!8-)"
ram@shukra.Sun.COM (Renu Raman) (10/21/88)
In article <3352@pt.cs.cmu.edu> ralphw@ius3.ius.cs.cmu.edu (Ralph Hyre) writes: >In article <3924@encore.UUCP> bzs@xenna (Barry Shein) writes: >>>Does Mach (on a NeXT, at any rate) do memory swapping to disk? >>>If so, what does it use for the swap area at times when the laser disk is out? >>I'll stick my neck out and say that I don't believe that you'll be >>able to remove the optical disk if that's what you're paging and >>swapping to > What if you can swap over the network? I thought that was possible in Mach. change your swap area to the big server's filesystem that is remote mounted and continue to swap your disks as you please. Renu Raman
bernard@boulder.Colorado.EDU (Bernie Bernstein) (10/21/88)
In <73838@sun.uucp> ram@sun.UUCP (Renu Raman) writes: >In <3352@pt.cs.cmu.edu> ralphw@ius3.ius.cs.cmu.edu (Ralph Hyre) writes: >>In <3924@encore.UUCP> bzs@xenna (Barry Shein) writes: >>>>Does Mach (on a NeXT, at any rate) do memory swapping to disk? >>>>If so, what does it use for the swap area when the laser disk is out? >>>I'll stick my neck out and say that I don't believe that you'll be >>>able to remove the optical disk if that's what you're paging and >>>swapping to > What if you can swap over the network? > I thought that was possible in Mach. > change your swap area to the big server's filesystem that is > remote mounted and continue to swap your disks as you please. Oh yeah, and let one CPU manage the paging for the entire network. Then we can see some real wild thrashing.:-> I think what is necessary is paging to the local disk. It should be a fast one, so if the seek rates on the optical disk are above 30ms, then perhaps a Wren (16.5ms) or some other traditional hard disk should be used. Otherwise, we can keep the optical disk in and go along with Ralph's hypothesis: don't let the disk out unless we're ready ... - Bernie ----------------------------------------------------------------------------- Bernie Bernstein bernard@boulder.colorado.edu
rk@lexicon.UUCP (Bob Kukura) (10/21/88)
In article <4200@boulder.Colorado.EDU> bernard@boulder.Colorado.EDU (Bernie Bernstein) writes:
Oh yeah, and let one CPU manage the paging for the entire network.
Then we can see some real wild thrashing.:->
I think what is necessary is paging to the local disk. It should be a
fast one, so if the seek rates on the optical disk are above 30ms, then
perhaps a Wren (16.5ms) or some other traditional hard disk should be used.
Otherwise, we can keep the optical disk in and go along with Ralph's
hypothesis: don't let the disk out unless we're ready ...
Since MACH can swap to free space on any filesystem, I would set up
NeXT machines in an NFS network environment as follows:
* boot from a network server
* mount root, /usr (and /var) via NFS, with all NeXT machines sharing
the same /usr
* install a small fast winchester disk on each machine mounted as /tmp
and swap on this
* mount the floptical disk as /usr/user with some hack so that it is
automatically mounted when it is inserted and unmounted when it is
removed
This setup seems pretty optimal to me in terms of performance,
administration, user convenience, and security. Swapping and most
file writes of a temporary nature are on the winchester, so they are
fast and don't wear out the floptical disk. All system software and
educational software is centrally maintained, with no system
configuration local to the machine. The /tmp filesystem could be
recreated each time the machine boots. Users take their own files and
software with them on their floptical disks.
--
-Bob Kukura uucp: {husc6,linus,harvard,bbn}!spdcc!lexicon!rk
phone: (617) 891-6790jt@edge.UUCP (J.T. McDuffie) (10/27/88)
We keep talking about needing lots of swap space. How much do you need? On our big company system ( > 60 users) we have a swap partition of 16MB. If you are running on a single user system with 16MB+ of memory, I wouldn't think you'd need much, if any, swap. In that case, the single removable disk is not a problem. +==========================================================================+ | Disclamer: My opinions are my own. No one else seems to want them! | +==========================================================================+ | JT McDuffie, Edgcore Technology (formerly Edge Computer), Scottsdale, AZ | | {ames,hplabs,sun,amdahl,allegra}!oliveb!edge!jt uunet!ism780c!edge!jt | +==========================================================================+
landman%hanami@Sun.COM (Howard A. Landman) (10/29/88)
In article <1294@edge.UUCP> jt@edge.UUCP (J.T. McDuffie) writes: >We keep talking about needing lots of swap space. How much do you need? >On our big company system ( > 60 users) we have a swap partition of >16MB. If you are running on a single user system with 16MB+ of memory, >I wouldn't think you'd need much, if any, swap. In that case, the >single removable disk is not a problem. That's because you're talking about users who never do anything much heavier than edit a file. In the CAD realm, demands are much higher. Swap space of 100 MB is recommended for the Genesil silicon compiler, alone. And some simulator people I respect have told me that any system with less than 40 MB memory is useless for serious simulation work. These requirements pale next to the requirements for image-processing applications. Some imaging spectrophotometers deliver nearly a gigabyte PER IMAGE. If you want to keep an image in virtual memory, you need a gigabyte of swap. My Sun3 has 12 MB memory and 40 MB swap; but I don't do anything too massive on it. There are servers for that sort of thing ... Howard A. Landman landman@hanami.sun.com UUCP: sun!hanami!landman