Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site decvax.UUCP Path: utzoo!watmath!clyde!floyd!harpo!decvax!jmcg From: jmcg@decvax.UUCP (Jim McGinness) Newsgroups: net.unix-wizards Subject: Re: Question on strategy() routines for 4.1BSD drivers Message-ID: <415@decvax.UUCP> Date: Thu, 22-Mar-84 15:59:52 EST Article-I.D.: decvax.415 Posted: Thu Mar 22 15:59:52 1984 Date-Received: Fri, 23-Mar-84 21:17:24 EST References: <222@hou2d.UUCP> Organization: DEC UNIX Engineering Group Lines: 18 The invalid fill-on-demand-from-inode pages are made valid in uba or mba maps by the other drivers before the transfer occurrs, then validated by `pagein'. Your driver should just validate the pages in place and move the bytes. It is probably necessary to raise your priority while you do it, since another process running that image might sneak in and find the valid page and try to execute the old bytes. Better would be to invert the sense of the `copyseg' routine to move from physical address to user virtual address. If you have memory to burn, however, I've found that it makes sense to increase your number of buffers (and on 4.2 to increase bufpages). This has the effect of keeping more of the disk in memory, but is not as direct as targeting a particular file system to actually reside in memory. Jim McGinness decvax!jmcg Digital Equipment Corp. (603)844-5703 MKO2-1/H10 Merrimack, NH, 03054