Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!caen!umich!sharkey!nstar!larry
From: larry@nstar.rn.com (Larry Snyder)
Newsgroups: comp.unix.sysv386,fido.unix
Subject: Re: Kernel panic w/heavy disk I/O (ISC)
Message-ID: <1991Mar02.231720.456@nstar.rn.com>
Date: 2 Mar 91 23:17:20 GMT
References: <176@xyzoom.UUCP> <1991Feb19.134450.6095@nstar.rn.com> <1991Mar1.021228.19501@informix.com>
Organization: NSTAR Public Access Unix Site - 8 dial up lines - 4200 megabytes
Lines: 38

aland@informix.com (Colonel Panic) writes:

>Am I *blind*?  I've got TFM right in front of me, and the only DMA- or
>bus-related parm I can find is DMAEXCL... where did you find out about
>DMASPEED and BUSS*?   (or were these pre-2.2?)

no, your not blind - none if this is covered in the manual -

here is part of my file:


#define AHA_BUSON       9       /* 5&9 defaults */
#define AHA_BUSOFF      5       /* 10 & 5 were working until recently */

#define AHA_DMASPEED    4       /* 1 for 6.7 mhz, 2 for 8 mhz, 3 for 10 mhz */
				/* 4 for 5.7 mhz */

ok, the first two defs are 5 and 9 by default - as you can see
I have them reversed which increased disk IO by around 31% here on nstar

raising these paramaters too much will cause the floppy drive to overrun

next is DMA Speed - I have mine at 4 (5.7mhz) - my other motherboard
(a SOYO) supported up to 8 megs (2) without problems but my current
386/33 can't handle anything higher than 5.7 without cause problems
when the systems gets very loaded

by tweaking these defs and rebuilding the kernel it is possible to
make a noticable increase in diskio -- but it is also possible to
screw up your disk - -

use caution - and make backups --


-- 
   Larry Snyder, NSTAR Public Access Unix 219-289-0287 (HST/PEP/V.32/v.42bis)
                        regional UUCP mapping coordinator 
               {larry@nstar.rn.com, ..!uunet!nstar.rn.com!larry}