Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!ucsd!sdd.hp.com!uakari.primate.wisc.edu!aplcen!wb3ffv!howardl From: howardl@wb3ffv.ampr.org ( WB3FFV) Newsgroups: comp.unix.i386 Subject: Re: Tuning aha1540 driver (ISC 2.2) Message-ID: <3695@wb3ffv.ampr.org> Date: 18 Aug 90 23:39:41 GMT References: Organization: Advanced Business Solutions - Baltimore , MD Lines: 58 From article , by larry@focsys.uucp (Larry Williamson): > > My tests seem to indicate that the default values for BUSON, BUSOFF > and DMASPEED are the fastest. > > With BUSON 5, BUSOFF 9 and DMASPEED 0; the system seems to be > performing just fine. Have you tried to use any other settings? Roy Neese at Adaptec strongly recomended setting BUSON=7 and BUSOFF=4. I would think increasing the BUSON time would be a BIG help. I have heard of several people using a BUSON of 9 and a BUSOFF of 6, but haven't tried that on my side, as Roy's recomendations seem to work great. > I'm not entirely sure how to modify the DMASPEED parameter. Values of > 0 and 1 seem to work, but 2 causes the system to enter the kernel > debugger at boot time. I've not bothered trying a value of 3. How do > these values relate to the DMA speeds of 5, 5.7, 6.7 and 8 Mhz that > the controller is supposed to be able to support? Is it the obvious > 0->5, 1->5.7, 2->6.7, 3->8? Here are the various setting for the DMASPEED: 0 = 5.0 MBytes/sec 1 = 6.7 MBytes/sec 2 = 8.0 MBytes/sec 3 = 10.0 MBytes/sec 4 = 5.7 MBytes/sec To find the highest possible setting you can use on your system, try using the Bus Mastering Test which is located in ROM at location dc00:9 > The test bed system I'm using is an AMI MB with 4 Meg ram, 64K cache > and 20 Mhz clock. I placed a Adaptec 1542B controller in a 20mhz machine and have it running at an 8mhz (DMASPEED=2) DMA rate, but this is highly system dependant. > During these tests I've left the DMA speed selection header on the > board open. This selects the default of 5 Mhz. I'm going to try > other selections on the jumpers. Is there a reason why this is not a > good idea? This is the correct way to try it, but be sure to run the Bus Mastering Tests under MS/DOG in the ROM that I mentioned above. > Any advise you can offer would be greatly appreciated. Thanks. Well there it is, the whole two cents worth! > -Larry ------------------------------------------------------------------------------- Internet : howardl@wb3ffv.ampr.org | Howard D. Leadmon UUCP : wb3ffv!howardl | Advanced Business Solutions TELEX : 152252474 | 210 E. Lombard St - Suite 410 Telephone : (301)-576-8635 | Baltimore, MD 21202