From owner-freebsd-stable@FreeBSD.ORG Sun Feb 3 23:38:08 2008 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 531DC16A41B for ; Sun, 3 Feb 2008 23:38:08 +0000 (UTC) (envelope-from freebsd-stable@m.gmane.org) Received: from ciao.gmane.org (main.gmane.org [80.91.229.2]) by mx1.freebsd.org (Postfix) with ESMTP id 7F89F13C442 for ; Sun, 3 Feb 2008 23:38:06 +0000 (UTC) (envelope-from freebsd-stable@m.gmane.org) Received: from list by ciao.gmane.org with local (Exim 4.43) id 1JLoPP-0001gF-3R for freebsd-stable@freebsd.org; Sun, 03 Feb 2008 23:37:59 +0000 Received: from 78-1-113-112.adsl.net.t-com.hr ([78.1.113.112]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 03 Feb 2008 23:37:59 +0000 Received: from ivoras by 78-1-113-112.adsl.net.t-com.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sun, 03 Feb 2008 23:37:59 +0000 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-stable@freebsd.org From: Ivan Voras Date: Mon, 04 Feb 2008 00:37:43 +0100 Lines: 73 Message-ID: References: <3aaaa3a0802030751w69ce59a9oeb869e3d87d92616@mail.gmail.com> <47A62B00.1060403@egr.msu.edu> <3aaaa3a0802031318y2e3fd33en8071c82172ab9ecf@mail.gmail.com> <47A63610.4070608@protected-networks.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigABE262E7FCBEA5D933381A10" X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 78-1-113-112.adsl.net.t-com.hr User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) In-Reply-To: <47A63610.4070608@protected-networks.net> X-Enigmail-Version: 0.95.6 Sender: news Subject: Re: gjournal panic 7.0-RC1 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Feb 2008 23:38:08 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigABE262E7FCBEA5D933381A10 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Michael Butler wrote: > I would think that journaling on one drive and storing the resultant=20 > data-set on another would improve performance enormously (reduced=20 > seek-lengths) and more so if they were 1) high-rpm drives (less=20 > rotational latency) and 2) on different buses (no bus/controller=20 > contention), There are (very near) limits to what you can do with such a setup: the=20 drive that holds the external journal needs to be much faster than the=20 data drive, since it will become the main bottleneck in IO. It has to be = faster mostly in sequential IO, seeks are only present when transferring = journal data to the main drives while under simultaneous write IO from=20 the file system. Ideally, the journal drive would have to deliver at=20 least twice as sequential IO as the main drive to maximize the potential = performance. Thus, using a conveniently small medium as an USB flash=20 drive is not very useful (the high seek rate will remain unused and=20 sequential performance is generally lower than regular drives) I've done some benchmarking. The setup is: three 7.5k RPM drives, two in = RAID0, one for the journal. Here's a summary of the results: UFS+SU: bonnie++: writes: 102 MB/s, rewrites: 47 MB/s, reads: 103 MB/s postmark: 110 trans/s UFS+GJ: bonnie++: writes: 35 MB/s, rewrites: 22 MB/s, reads: 99 MB/s postmark: 123 trans/s UFS+GJ-detached: bonnie++: writes: 46 MB/s, rewrites: 36 MB/s, reads: 100 MB/s postmark: 263 trans/s Postmark is configured to have a bias for writing a lot of small files,=20 and benefits a lot from the detached journal. Margins of errors are=20 around +/- 3 MB/s for bonnie++ and around 15 trans/s for postmark. For comparison, here are the results for Linux 2.6.23, regular ext3: bonnie++: writes: 105 MB/s, rewrites: 52 MB/s, reads: 128 MB/s postmark: 173 trans/s --------------enigABE262E7FCBEA5D933381A10 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHplBNldnAQVacBcgRAuMyAJ0ce6nqja0lrkrGRAInm8Xn74fZVQCgsl5h +N3qni0MsBUnACGru8blBno= =RTXJ -----END PGP SIGNATURE----- --------------enigABE262E7FCBEA5D933381A10--