From owner-freebsd-questions@FreeBSD.ORG Sun Jun 15 21:20:02 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 89EBA1065671 for ; Sun, 15 Jun 2008 21:20:02 +0000 (UTC) (envelope-from kris@FreeBSD.org) Received: from weak.local (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id 3A1448FC1E; Sun, 15 Jun 2008 21:20:01 +0000 (UTC) (envelope-from kris@FreeBSD.org) Message-ID: <48558782.9000703@FreeBSD.org> Date: Sun, 15 Jun 2008 23:20:02 +0200 From: Kris Kennaway User-Agent: Thunderbird 2.0.0.14 (Macintosh/20080421) MIME-Version: 1.0 To: RW References: <20080614224742.17316919@gumby.homeunix.com.> <48545212.4040006@FreeBSD.org> <20080615013158.7dd19cf0@gumby.homeunix.com.> <48546B92.5050906@FreeBSD.org> <20080615035555.0b5d4b1c@gumby.homeunix.com.> <4854FF77.80901@FreeBSD.org> <20080615185746.60efea11@gumby.homeunix.com.> In-Reply-To: <20080615185746.60efea11@gumby.homeunix.com.> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: md devices mounted with async X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 15 Jun 2008 21:20:02 -0000 RW wrote: > But isn't the normal point of async to avoid having the cpu waiting for > the disk with nothing to do. If there's nothing to block on, the cpu can > be consistently utilized without async. I suppose with SMP it might > help spread the work between cpus, but with a single cpu it seems like > it would just end-up doing the same work in a different order. Yes, but even on a single CPU your application can potentially dispatch more work in the meantime. e.g. it could be doing other device or network I/O. Kris