Date: Sun, 19 Sep 1999 10:22:50 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, dg@root.com, Greg Lehey <grog@lemis.com>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: User block device access (was: cvs commit: src/sys/miscfs/specfs spec_vnops.c src/sys/sys vnode.h src/sys/kern vfs_subr.c) Message-ID: <Pine.BSF.4.05.9909191020230.41966-100000@semuta.feral.com> In-Reply-To: <199909191715.KAA72822@apollo.backplane.com>
next in thread | previous in thread | raw e-mail | index | archive | help
> :My position is a little bit more flexible: I don't care which of > :the two interfaces we retain, as long as we only have one and as > :long as it isn't buggy (ie: it should return write errors). > : > :The argument for the block device is that it *is* more "unix feel" to > :be able to read and write at any byte and with any length. > : > :IFF we want to maintain the block interface, we need to fix the error > :return for the write case, but we also need to do a significant amount > :of work speeding it up. It currently is an order of magnitude slower > :than the char interface (remember to measure consumed CPU time, not > :wall-clock time). > : > :For anyone with a second disk or floppy drive in their system, attempting > :to fix the block dev interface is not a very hard problem. > : > :-- > :Poul-Henning Kamp FreeBSD coreteam member > > The buffered block device is not slow, I don't know where you get > that idea from. It is, in fact, just about as fast as you can get and > still cache the data, which is to say somewhat faster then normal file > access would be. The cache is flushed on every open of the device > which may be causing your confusion. There is no overhead beyond the > normal overhead associated with caching a file. It can be slow for reads, but fast for writes if you have a good clustering mechanism. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.05.9909191020230.41966-100000>