Path: utzoo!utgpu!water!watmath!clyde!cbosgd!mandrill!nitrex!rbl From: rbl@nitrex.UUCP ( Dr. Robin Lake ) Newsgroups: comp.unix.wizards Subject: Re: /dev/swap - possibility of it being a ramdisk Summary: /dev/swap as a ramdisk has been evaluated Message-ID: <585@nitrex.UUCP> Date: 11 Dec 87 20:20:35 GMT References: <712@qetzal.UUCP> Reply-To: rbl@nitrex.UUCP ( Dr. Robin Lake ) Organization: The Standard Oil Co., Cleveland Lines: 36 In article <712@qetzal.UUCP> rcw@qetzal.UUCP (Robert C. White) writes: >Hello Wizards, > >Watching my poor little unix boxes swap, it occurred to me: >why not utilize some extra ram to implement /dev/swap? It seems that >the machine would speed up quite a bit, and hey, extra memory >is pretty inexpensive, at least for the smaller >unix boxes. Also, it would be tactically easier to >increase the amount of "swap" memory as opposed to repartitioning >my disks, or mounting a disk pack under /tmp or some other >horrid kludge. About 10 years ago, I was involved with the design of a "solid-state disk" --- a ram disk that looked like a fixed-head disk for PDP-11 Unibus machines. A graduate student of mine did his Ph.D. dissertation on the performance of UNIX with such a box. (Sugit Kumar, Case Western Reserve University). Bottom line was that you want TWO such "ramdisks", one for /tmp or /usr/tmp and one for the commonly used programs (/bin, /usr/bin). The only shortcoming is that the device drivers and the I/O strategies of the kernel consume relatively huge amounts of time per "disk" access. The result is that a solid-state device (17,000 times faster transfer rate than a rotating disk) only performs 10 to 50 times better. Nonetheless, watch for significant new computer architectures from the 3-letter computer vendors which take advantage of more ram memory than you might have ever believed would fit in a box! Exciting times ahead.... Rob Lake BP America R&D (ex-Principal Scientist, Monolithic Systems Corp - mfgr. of "Extended Memory Unit" ) decvax!mandrill!nitrex!rbl 216-581-5976 -- Rob Lake {decvax,ihnp4!cbosgd}!mandrill!nitrex!rbl