Xref: utzoo comp.unix.microport:426 comp.unix.xenix:1880 Path: utzoo!mnetor!uunet!husc6!spdcc!dyer From: dyer@spdcc.COM (Steve Dyer) Newsgroups: comp.unix.microport,comp.unix.xenix Subject: Re: RAM disk Message-ID: <802@spdcc.COM> Date: 8 Apr 88 01:22:53 GMT References: <1010@daisy.UUCP> Organization: S.P. Dyer Computer Consulting, Cambridge MA Lines: 30 In article <1010@daisy.UUCP>, david@daisy.UUCP (David Schachter) writes: > With the recent discussion of problems running 9600 bps without losing char- > acters, someone bemoaned the inability to define in-memory filesystems. Is > there really no Unix driver to define in-memory simulated disk? For some > applications, such a facility would yield a substantial speed improvement > without the need to alter the application for better memory buffering. XENIX 2.2 and above has a RAM disk driver, although I have never bothered to use it; at least on XENIX 386, it's far more effective to give all your memory to the paging system. I could imagine that certain specific applications might benefit from using some of the memory as a RAM disk, and perhaps a XENIX 286 system with just plain too much memory, given a certain application demand, could show a benefit. The nice thing about XENIX is you can try it with and without a RAM disk and make up your own mind. Needless to say, none of this deserves to be mentioned in the same breath as losing characters at 9600 baud. Neither XENIX 286 or XENIX 386 loses characters no matter how hard its disks are pushed. I run 4 dumb serial lines under XENIX 386, one at 9600, one at 19.2kb, and the other two at 2400 baud. Even with all of them active, I've never had any problem. If Microport drops characters, it's because of problems in their kernel (undoubtedly too frequent or inappropriate spl() calls sprinkled throughout) and not because the disk is getting banged on. I'd pressure them to get their drivers cleaned up; from what I've heard, it wouldn't surprise me if a RAM disk driver from them would show the same problems! -- Steve Dyer dyer@harvard.harvard.edu dyer@spdcc.COM aka {ihnp4,harvard,husc6,linus,ima,bbn,m2c}!spdcc!dyer