From owner-freebsd-stable@FreeBSD.ORG Sun Feb 14 20:26:21 2010 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 69CB2106568B for ; Sun, 14 Feb 2010 20:26:21 +0000 (UTC) (envelope-from jon@witchspace.com) Received: from mtaout03-winn.ispmail.ntl.com (mtaout03-winn.ispmail.ntl.com [81.103.221.49]) by mx1.freebsd.org (Postfix) with ESMTP id B5D9B8FC1C for ; Sun, 14 Feb 2010 20:26:20 +0000 (UTC) Received: from aamtaout01-winn.ispmail.ntl.com ([81.103.221.35]) by mtaout03-winn.ispmail.ntl.com (InterMail vM.7.08.04.00 201-2186-134-20080326) with ESMTP id <20100214202618.BYBY10950.mtaout03-winn.ispmail.ntl.com@aamtaout01-winn.ispmail.ntl.com> for ; Sun, 14 Feb 2010 20:26:18 +0000 Received: from witchspace.com ([86.28.98.4]) by aamtaout01-winn.ispmail.ntl.com (InterMail vG.2.02.00.01 201-2161-120-102-20060912) with SMTP id <20100214202618.JBZG13254.aamtaout01-winn.ispmail.ntl.com@witchspace.com> for ; Sun, 14 Feb 2010 20:26:18 +0000 Received: (qmail 17799 invoked from network); 14 Feb 2010 19:26:02 -0000 Received: from unknown (HELO core.home) (192.168.0.3) by 192.168.0.100 with SMTP; 14 Feb 2010 19:26:02 -0000 Mime-Version: 1.0 (Apple Message framework v1077) Content-Type: text/plain; charset=us-ascii From: Jonathan Belson In-Reply-To: Date: Sun, 14 Feb 2010 20:26:15 +0000 Content-Transfer-Encoding: quoted-printable Message-Id: <50780815-0D98-4910-B81A-1F41455AC856@witchspace.com> References: To: Artem Belevich X-Mailer: Apple Mail (2.1077) X-Cloudmark-Analysis: v=1.1 cv=W3tOLUehizD4qj6VhtReFuw5MKb8d+XqjIxlDsIazEA= c=1 sm=0 a=uaAj8Ayxam7Zkd_fM5QA:9 a=fKIaMkIs0kY3gXFDgKPSimqX4ZEA:4 a=HpAAvcLHHh0Zw7uRqdWCyQ==:117 Cc: freebsd-stable@freebsd.org Subject: Re: More zfs benchmarks 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, 14 Feb 2010 20:26:21 -0000 On 14 Feb 2010, at 19:13, Artem Belevich wrote: > Can you check if kstat.zfs.misc.arcstats.memory_throttle_count sysctl > increments during your tests? >=20 > ZFS self-throttles writes if it thinks system is running low on > memory. Unfortunately on FreeBSD the 'free' list is a *very* > conservative indication of available memory so ZFS often starts > throttling before it's really needed. With only 2GB in the system, > that's probably what slows you down. I tested a number of times during a 2GB write to a zfs partition and the = count stayed at 0. Cheers, --Jon