Date: Sun, 22 Mar 2009 14:02:20 +0100 From: Ivan Voras <ivoras@freebsd.org> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: Pawel Jakub Dawidek <pjd@freebsd.org>, luigi@freebsd.org, Luigi Rizzo <rizzo@iet.unipi.it>, freebsd-geom@freebsd.org Subject: Re: disk scheduling (was: Re: RFC: adding 'proxy' nodes to provider ports (with patch)) Message-ID: <9bbcef730903220602q736b96dflab447e2d6d996754@mail.gmail.com> In-Reply-To: <45710.1237709582@critter.freebsd.dk> References: <eb21ef440903211800h266ec0aes158cb189095289c1@mail.gmail.com> <45710.1237709582@critter.freebsd.dk>
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2009/3/22 Poul-Henning Kamp <phk@phk.freebsd.dk>: > In message <eb21ef440903211800h266ec0aes158cb189095289c1@mail.gmail.com>, Luigi > Rizzo writes: > >>The thread was meant to be on inserting transparent nodes in GEOM. >> >>Scheduling was just an example on where the problem came out, > > Scheduling is the *only* application I have seen mentioned for > this special case geom construct ? I've joined this thread because once upon a time I was working on what has grown into gjournal, and one aspect of the original project was a logging "safety net" mode. The idea was to insert this class (or whatever) just before a file system consumer then do risky things with the file system metadata (like fsck-ing a badly damaged file system), with the option of commiting it or rolling it back. It has even grown into another SoC project. I see now it doesn't comply with my idea of a "lightweight" proxy (the first item, about 1:1 mappings) - so proxies look more and more like they should be classes. Also, gcache looks like a candidate.
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