Date: Wed, 2 Oct 1996 12:40:10 -0500 (EST) From: John Dyson <dyson@dyson.iquest.net> To: dfr@render.com (Doug Rabson) Cc: dyson@freebsd.org, phk@critter.tfs.com, heo@cslsun10.sogang.ac.kr, freebsd-hackers@freebsd.org, freebsd-fs@freebsd.org Subject: Re: vnode and cluster read-ahead Message-ID: <199610021740.MAA01329@dyson.iquest.net> In-Reply-To: <Pine.BSF.3.95.961002181522.10204N-100000@minnow.render.com> from "Doug Rabson" at Oct 2, 96 06:21:13 pm
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> > You could maintain a number of 'pending readahead' structures indexed by > vnode and block number. Each call to cluster_read would check for a > pending readahead by hashing. For efficiency, keep a pointer to the last > readahead structure used by cluster_read in the vnode in place of the > existing in-vnode readahead data. Should be no slower than the current > system for single process reads and it saves 4 bytes per vnode :-). > Pretty cool idea. I am remembering now that this deficiency in our read ahead code is well known. This might be something really good for 2.3 or 3.1 :-). (Unless someone else wants to implement it -- hint hint :-)). John
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