From owner-freebsd-current@FreeBSD.ORG Thu Apr 16 13:23:05 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5BFDC1065670 for ; Thu, 16 Apr 2009 13:23:05 +0000 (UTC) (envelope-from peter.schuller@infidyne.com) Received: from hyperion.scode.org (cl-1361.ams-04.nl.sixxs.net [IPv6:2001:960:2:550::2]) by mx1.freebsd.org (Postfix) with ESMTP id 189168FC13 for ; Thu, 16 Apr 2009 13:23:05 +0000 (UTC) (envelope-from peter.schuller@infidyne.com) Received: from hyperion.scode.org (hyperion.scode.org [85.17.42.115]) by hyperion.scode.org (Postfix) with ESMTPS id C8C9C2394AA; Thu, 16 Apr 2009 15:23:03 +0200 (CEST) Date: Thu, 16 Apr 2009 15:23:02 +0200 From: Peter Schuller To: Artem Belevich Message-ID: <20090416132302.GA86096@hyperion.scode.org> References: <49C2CFF6.8070608@egr.msu.edu> <08D7DC2A-68BE-47B6-8D5D-5DE6B48F87E5@wanderview.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="rwEMma7ioTxnRzrJ" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.19 (2009-01-05) Cc: freebsd-current@freebsd.org, Ben Kelly Subject: Re: [patch] zfs livelock and thread priorities X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Apr 2009 13:23:05 -0000 --rwEMma7ioTxnRzrJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > BTW, now that you're tinkering with ZFS threads and priorities, whould > you by any chance have any idea why zfs scrub is so painfully slow on > -current? > When I start scrub on my -stable box, it pretty much runs full speed > -- I can see disks under load all the time. > However on -current scrub seems to run in small bursts. Disks get busy > for a second or so and then things get quiet for about five seconds or > so and this pattern repeats over and over. This is intentional. The newer ZFS code has, if I remember correctly, something like "spend at most 1/5 of the time doing scrub for each underlying vdev". I could be wrong on the details and I don't have source refs off-hand, by I looked into this when I wanted to see if I could tweak this (while I definitely like it rate limited, I would have liked to up the threshold a bit). My conclusion at the time was that there was no way to tweak it other than recompiling the kernel. --=20 / Peter Schuller PGP userID: 0xE9758B7D or 'Peter Schuller ' Key retrieval: Send an E-Mail to getpgpkey@scode.org E-Mail: peter.schuller@infidyne.com Web: http://www.scode.org --rwEMma7ioTxnRzrJ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.11 (FreeBSD) iEYEARECAAYFAknnMTYACgkQDNor2+l1i336pACggYkwt6NFavYiTKKYZ3OH9EEK oK0AmwVcai3KXjdYK/C2Yaa3/aRC4W4h =K1CW -----END PGP SIGNATURE----- --rwEMma7ioTxnRzrJ--