Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!clyde.concordia.ca!nstn.ns.ca!news.cs.indiana.edu!julius.cs.uiuc.edu!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!ucbvax!mtxinu!taniwha!paul From: paul@taniwha.UUCP (Paul Campbell) Newsgroups: comp.sys.m68k Subject: Re: Need 68030 SYSV Box Message-ID: <774@taniwha.UUCP> Date: 8 Feb 91 17:34:13 GMT References: <1991Feb6.182148.14806@demott.com> <1646@peritek.UUCP> Reply-To: paul@taniwha.UUCP (Paul Campbell) Organization: Taniwha Systems Design, Oakland Lines: 36 In article <1646@peritek.UUCP> dig@peritek.UUCP (Dave Gotwisner) writes: >In article <1991Feb6.182148.14806@demott.com>, kdq@demott.com (Kevin D. Quitt) writes: >> >> We are currently using Motorola's Delta 3000 series machines (25MHz >> 68030), and we generally like them, but we've stumbled onto a problem. >> It appears that Motorola's UNIX buffers pipes onto disk, and our product > >Actually, all UNIX systems that I have ever dealt with (from Version 6 through >SVR3 and 4.3BSD) have put pipes on disk, usually in the root filesystem. This >is a standard UNIXism. If this is not acceptable for your environment, you can Actually neither of these statements is strictly true, what Unix does is it grabs a few disk buffers to put the pipe's buffered information in before it's read. If the consuming task waits around for too long before grabbing the data the buffers will get flushed out to disk because someone else wants to use them (or because sync comes along). Usually the pipe is busy enough that the data is flowing though it without making a trip to disk. If your system is busy doing lots of other disk IO (which may cause your pipe bufferes to be flushed to disk more) and you have a time critical application you might have to think about using another IPC mechanism like sockets or messages or shared memory/semaphores any of which will probably do the job and wont involve disk IO. Another possibility is to increase the size of the buffer cache. This way of storing pipe info is sort of a poor man's VM (and a neat hack on the part of the original implementors).. Paul -- Paul Campbell UUCP: ..!mtxinu!taniwha!paul AppleLink: CAMPBELL.P 'Where do you find a "kinder gentler nation" when you need one these days?' The proper solution to this mess is to lock Bush and Hussein in a room - and throw away the key - that way everyone can go home.