From owner-freebsd-fs@FreeBSD.ORG Thu Aug 9 23:11:48 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E5437106564A for ; Thu, 9 Aug 2012 23:11:48 +0000 (UTC) (envelope-from bfriesen@simple.dallas.tx.us) Received: from blade.simplesystems.org (blade.simplesystems.org [65.66.246.74]) by mx1.freebsd.org (Postfix) with ESMTP id 8153C8FC20 for ; Thu, 9 Aug 2012 23:11:48 +0000 (UTC) Received: from freddy.simplesystems.org (freddy.simplesystems.org [65.66.246.65]) by blade.simplesystems.org (8.14.4+Sun/8.14.4) with ESMTP id q79N0ujN003638; Thu, 9 Aug 2012 18:00:56 -0500 (CDT) Date: Thu, 9 Aug 2012 18:00:56 -0500 (CDT) From: Bob Friesenhahn X-X-Sender: bfriesen@freddy.simplesystems.org To: Daniel Kalchev In-Reply-To: <5023D9B7.20001@digsys.bg> Message-ID: References: <5023D9B7.20001@digsys.bg> User-Agent: Alpine 2.01 (GSO 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (blade.simplesystems.org [65.66.246.90]); Thu, 09 Aug 2012 18:00:56 -0500 (CDT) Cc: freebsd-fs@freebsd.org Subject: Re: ZFS scrub CPU bound? X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 Aug 2012 23:11:49 -0000 On Thu, 9 Aug 2012, Daniel Kalchev wrote: > > What might be there in ZFS code that is single-CPU bound? Almost certainly there is a single brain at the top to dictate the scrub algorithm. Scrub does need to proceed in appropriate order. Some things are best left for one CPU to do. It is unlikely that FreeBSD's I/O system is optimized for SSDs. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/