From owner-freebsd-stable@FreeBSD.ORG Tue Nov 16 15:53:58 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 97E921065670 for ; Tue, 16 Nov 2010 15:53:58 +0000 (UTC) (envelope-from christer.solskogen@gmail.com) Received: from mail-pv0-f182.google.com (mail-pv0-f182.google.com [74.125.83.182]) by mx1.freebsd.org (Postfix) with ESMTP id 6A2378FC17 for ; Tue, 16 Nov 2010 15:53:58 +0000 (UTC) Received: by pvc22 with SMTP id 22so149789pvc.13 for ; Tue, 16 Nov 2010 07:53:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:cc:content-type; bh=NyZ8o/UmEQRnY6K/wdcS7h1hhencWChzEhV1jR13c84=; b=g458vAvXTSQOOJe061KwXtvX32bbPxHry9CuFu01fnAXdmkNPzCRZHrPgdBBq/IcWp T5fqCFMW2rcycpEydC2IwC5UXTMqgyJpQCVzUVzoRrfjSuLJiYIjDL6pq85nbCUX0pjS sDi1wmGa9hL5zCvFkVEMbsoySNKvRsOaGhGUo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=Mjcmi0aPGrybSwRnCdk+uHzbqWSXTOI+WiMI5Pk8dPsFU9OsP1cJX9wXBm0J+nbtsS ZHiJ2qUt4IUpvJmjW1qyRfwG+Xs69ayGoxF0xXd5ls7lKXC//NFlmcUaQlgMDPV/HEaT IvAfOnh4jPw/tHV750zbs0kjn1hMdbeFhydZk= MIME-Version: 1.0 Received: by 10.229.82.10 with SMTP id z10mr6499383qck.98.1289922837425; Tue, 16 Nov 2010 07:53:57 -0800 (PST) Received: by 10.229.231.81 with HTTP; Tue, 16 Nov 2010 07:53:57 -0800 (PST) In-Reply-To: <20101116131128.GB21229@rron.local> References: <20101116003029.GC79816@numachi.com> <20101116131128.GB21229@rron.local> Date: Tue, 16 Nov 2010 16:53:57 +0100 Message-ID: From: Christer Solskogen To: Ollivier Robert Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-stable@freebsd.org Subject: Re: "High" cpu usage when using ZFS cache device 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: Tue, 16 Nov 2010 15:53:58 -0000 On Tue, Nov 16, 2010 at 2:11 PM, Ollivier Robert wrote: > According to Christer Solskogen: >> See, that is why I think it is a ZFS issue. Because I did that. >> I created a UFS filesystem on the same usb stick. Mounted it and did a >> "dd if=/dev/zero of=/mnt/file". >> The systemload goes +0.6 instead if +10.3. > > Do not forget that everything that is read/written from/to USB devices goes through the CPU (no DMA or anything for USB devices). > I didn't forget that. Thats why I also tested with UFS. And I do not have the same issue with that. With top -HS I discovered this: 5 root -8 - 0K 76K zio->i 4 403.2H 85.06% {l2arc_feed_threa} -- chs,