Date: Thu, 27 Aug 1998 15:32:09 +0000 From: Mike Smith <mike@smith.net.au> To: zhihuizhang <bf20761@binghamton.edu> Cc: hackers <freebsd-hackers@FreeBSD.ORG> Subject: Re: FFS questions Message-ID: <199808271532.PAA00757@dingo.cdrom.com> In-Reply-To: Your message of "Thu, 27 Aug 1998 12:20:14 -0400." <Pine.SOL.L3.93.980827120824.10706A-100000@bingsun1>
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> > I am reading the source code in fs.h and the parameter fs_cpc confuses me. > > The comment says it is the number of cylinders per *cycle* in position > table. What does the "cycle" mean? It's the size of the rotational offset table. Starting from position 0 on the disk, there are N cycles of fastest-next-block locations as you move across the disk. You only need to store one cycle in the offset table. The position table and all the optimisations related to second-guessing the behaviour of the disk are now pessimisations in most cases, and should be eliminated entirely. Doing this is quite a job of work, and at the moment we simply short-circuit them. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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