Date: Tue, 12 Sep 1995 16:10:29 +0000 From: "Peter May" <peter@osix.com.au> To: J Wunsch <j@uriah.heep.sax.de>, hackers@freebsd.org Subject: Re: higher density diskettes Message-ID: <199509121557.PAA17050@thumper.osix.com.au>
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> As Peter May wrote: > > > That should speed the performance of this already flaky driver up no > > end! :-) > > Badly designed: yes. But flakey? How? Why? The "Task" I have assigned myself over the last 18 months or so has been the MCA support. The major stumbling block here was getting the driver to work with an architecture that supported all of the features that the '765 was supposed to - like the diskette changed line and so forth. Then add to that the layer of issues brought about by level sensitive interrupt handlers. IRQ's that are not reset by the driver (in the current architecture, which uses fdstate like fdintr :-( ) interrupt requests are not services at appropriate times, and fdstate fails to transition in many places or supply proper commands in all circumstances (like diskette changed). Now, I had this working reasonably on 1.1.5.1R, then along came 2.0R. A week later, I had "repaired" all of the issues (none of which I corrected in any form of elegance, BTW). The 2.0.5 - more major changes to the FD driver. Now I use SUP .... and follow -current, I am sure I am going to win the race to get the driver that I "need" working! Mind you, a lot of these issues only become apparent when you use an MCA machine ... but it leaves me wondering if some of the inconsistencies in the ISA stuff become obvious on MCA. > We've got one of the fastest floppy disk drivers. :-) It's even about > 10 % faster than Linux (for sequential reads), i've heard that old > Xenix' are as fast, and it's way faster than all commercial Unices > i've seen. (For sequential reads, and i consider them the most > typical _unix_ usage [tar floppy], we get 30 KB/s, that's 2/3 of the > raw data rate, and basically proves that we don't use revolutions.) On ISA, performance is great. > Of course, all this assumes that you're issuing larger requests than > single-sector, otherwise the o/s overhead may come into your way and > make you lose revolutions. > -- > cheers, J"org > > joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ > Never trust an operating system you don't have sources for. ;-) Best Regards, ---------------------------------------------------------------->>>>> Peter May OSIX Pty Ltd Director Level 1, 261-263 Pacific Highway Technical Services North Sydney. NSW. Australia. 2060. Home: +61-18-782858 Internet: peter@osix.com.au Work: +61-2-9922-3999 Fax: +61-2-9922-3385 >>>> PGP Public key available upon request <<<< ---------------------------------------------------------------->>>>>
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