Xref: utzoo comp.sys.mac:15771 comp.unix.aux:152 Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!mcnc!decvax!mandrill!nitrex!rbl From: rbl@nitrex.UUCP ( Dr. Robin Lake ) Newsgroups: comp.sys.mac,comp.unix.aux Subject: Re: MAC II ROM Upgrade Message-ID: <741@nitrex.UUCP> Date: 7 May 88 02:45:37 GMT References: <1895@polyslo.UUCP> <8546@apple.Apple.Com> <4050@dasys1.UUCP> <1558@pt.cs.cmu.edu> <981@aimt.UUCP> Reply-To: rbl@nitrex.UUCP ( Dr. Robin Lake ) Organization: BP America Research and Development Lines: 36 In article <981@aimt.UUCP> breck@aimt.UUCP (Robert Breckinridge Beatie) writes: >In article <1558@pt.cs.cmu.edu>, ralphw@IUS3.IUS.CS.CMU.EDU (Ralph Hyre) writes: >> In article <8972@apple.Apple.Com> phil@apple.UUCP (Phil Ronzone) writes: >> >Yes, I've have seen the National Semi boards working. I use one myself. >> >I have seen 5 boards in one system (88 megabytes of memory) running. >> >> Neat! So, has anyone tried porting the BSD ramdisk driver to A/UX? >> That's one way to sort of get more free space elsewhere, since you could put >> /tmp and multiple swap areas on multiple boards. ... > >Swap to ram? I like the idea of /tmp (and /usr/tmp for that matter) on >a ram disk. And then the system might benefit from having the pipe device >be a ram disk. But swap space? You're decreasing your available memory, >which causes more swapping. It seems that just keeping that memory available >to programs would eliminate swapping almost entirely. > Experiments with UNIX and a solid-state disk [Sugit Kumar's Ph.D. dissertation, Case Western Reserve University, late '70's] showed that the best use of a zero-latency disk with UNIX was for /tmp, /usr/tmp, and commonly- used system programs. The reason that there is less gain with using it for a swap device is that there is only ONE rotational latency, then the whole swap area is written out to a contiguous disk file. On the usual file system files, you can incur a number of rotational latencies per file. Of course, I don't know how the AUX driver and hardware really work, nor what the interleave factor is on the hard disk. These would affect the results Sugit obtained, as he was working with a word-addressable disk. More details upon demand, if any. -- Rob Lake BP America Research and Development decvax!mandrill!nitrex!rbl mandrill.CWRU.EDU!nitrex!rbl