From owner-freebsd-questions@freebsd.org Wed Jun 21 16:15:57 2017 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id EC237D9306E for ; Wed, 21 Jun 2017 16:15:57 +0000 (UTC) (envelope-from wblock@wonkity.com) Received: from wonkity.com (wonkity.com [67.158.26.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "wonkity.com", Issuer "wonkity.com" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id C04277256A for ; Wed, 21 Jun 2017 16:15:57 +0000 (UTC) (envelope-from wblock@wonkity.com) Received: from wonkity.com (localhost [127.0.0.1]) by wonkity.com (8.15.2/8.15.2) with ESMTPS id v5LGFtH6008796 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 21 Jun 2017 10:15:55 -0600 (MDT) (envelope-from wblock@wonkity.com) Received: from localhost (wblock@localhost) by wonkity.com (8.15.2/8.15.2/Submit) with ESMTP id v5LGFtWS008793; Wed, 21 Jun 2017 10:15:55 -0600 (MDT) (envelope-from wblock@wonkity.com) Date: Wed, 21 Jun 2017 10:15:55 -0600 (MDT) From: Warren Block To: Tim Daneliuk cc: FreeBSD Mailing List Subject: Re: FreeBSD and Linux SSD Write Speeds In-Reply-To: <45657887-638e-bb6d-c318-7046fdea1ca6@tundraware.com> Message-ID: References: <45657887-638e-bb6d-c318-7046fdea1ca6@tundraware.com> User-Agent: Alpine 2.21 (BSF 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (wonkity.com [127.0.0.1]); Wed, 21 Jun 2017 10:15:55 -0600 (MDT) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Jun 2017 16:15:58 -0000 On Wed, 21 Jun 2017, Tim Daneliuk wrote: > Disclaimer: Tests below run on lightly loaded systems, but results are ... surprising: > > Test Case: dd if=/dev/zero of=foo bs=8M count=512 > > Linux 4.4.0-21-generic on a 2.66GHz Core2 Duo w/8GB memory, older OCZ SSD/ext4: 310MB/sec writes > > FreeBSD 10-STABLE on an 3.2 GHz Quad Core i5 w/8GB memory, newer Kingston SSD/ufs: 210MB/sec writes > > Results are repeatable. > > So, what is the likely culprit making FreeBSD 1/3 slower? The FreeBSD > system does does / nfs exported (which I don't quite yet understand > since all the nfs mount points are below it) at the moment, but there > is little or no nfs traffic. Is Linux doing write caching? They used to do that.