Date: Thu, 7 Oct 1999 11:57:26 +1000
From: Peter Jeremy <peter.jeremy@alcatel.com.au>
To: "Matthew D. Fuller" <fullermd@futuresouth.com>
Cc: freebsd-current@FreeBSD.ORG
Subject: Re: {a}sync updates (was Re: make install trick)
Message-ID: <99Oct7.115403est.40324@border.alcanet.com.au>
In-Reply-To: <19991006181542.S20768@futuresouth.com>
References: <99Oct6.103524est.40351@border.alcanet.com.au> <Pine.BSF.4.05.9910051831180.6368-100000@fw.wintelcom.net> <99Oct6.145359est.40347@border.alcanet.com.au> <19991006154419.O20768@futuresouth.com> <99Oct7.085536est.40332@border.alcanet.com.au> <19991006181542.S20768@futuresouth.com>
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On 1999-Oct-07 09:15:42 +1000, Matthew D. Fuller wrote: >Is this good, bad, ugly, or just inconsistent? On the one hand, you can >argue that 'sync should be sync should be sync, I don't bloody care, just >don't do anything async at all', since that's what it's supposed to do: >mount(8): > sync All I/O to the file system should be done synchronously. How detailed should the man page be? If it stated "all file data will be written synchronously, but inodes where the only update is atime and free block bitmaps are written asynchronously", would that be any clearer to a user who didn't have a detailed understanding of UFS? If you would like it to say something different, write some patches and send them in as a PR (keeping in mind phk's recent e-mail about green bikesheds). > sync atime updates will slow it >down, but on the flip side, if you're mounting sync in the first place >you don't care much for speed anyway. There should be fairly few writes to the root partition, so having these writes synchronous is not a big performance hit. On the other hand, there are probably a _lot_ of read accesses to devices in /dev and files in /bin (how many of your scripts begin #!/bin/sh?). Unless you specify NOATIME, each of these read accesses implies an atime update within the inode. Making these synchronous probably would be a big performance hit. Peter -- Peter Jeremy (VK2PJ) peter.jeremy@alcatel.com.au Alcatel Australia Limited 41 Mandible St Phone: +61 2 9690 5019 ALEXANDRIA NSW 2015 Fax: +61 2 9690 5982 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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