Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!CGEUGE54.BITNET!BARTHO From: BARTHO@CGEUGE54.BITNET (PAUL BARTHOLDI) Newsgroups: comp.lang.forth Subject: RE: Re: Forth Programs (was Forth learning curve) Message-ID: <9001021454.AA18400@jade.berkeley.edu> Date: 2 Jan 90 08:27:00 GMT Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: Forth Interest Group International List Organization: The Internet Lines: 33 >> I'm running Microport "Real Unix" System V/AT on my '286 box. It eats >> about 30% of the CPU cycles. > > This isn't so much the fault of Unix, and maybe not even the fault of the > port. It's the fault of the AT hardware, which was optimized for DOS, > not Unix. Mitch also claimed 3% for sun/unix. I am not shure these figures make any sense. If you have a single pure cpu task, then even 3% is too much and wasted (I once turned off entirely the OS during a long computation!) while when many tasks run jointly, share data, i/o etc, I am ready to accept even much more than 30% for the system if it does what I need. We also have a Microport "Real Unix" on a 286 that control a very fast dedicated controler on one side, and is linked via ethernet to a sun 3/60. The user sits on the sun. We could have done avery thing in Forth on the 286, shure, but unix was definitely much smoother, more resilient etc. Of course a lot of time is spend in the OS, but not necessarely wasted! Even in forth, I would have to fetch, share and release buffers, manage queues, enable/desable i/o etc At last, concerning the hardware and its influence on overhead, I entirely agree with Mitch. The only problem is that a lot a hardware exists now for the AT at a rather low cost, so that, even brain damaged and slowed down by wrongly designed MMU, it can still be a cost effective solution ... H A P P Y N E W Y E A R ! Paul Bartholdi Observatory of Geneva PS I have found on both IBM PC, XT and AT that the interrupt lines are not correctly terminated. It has no effect as long you are running DOS, but can be the cause of a lot of trouble with multitasking systems like unix and Minix. Could this be why you get 30% overhead ?