From owner-freebsd-current@freebsd.org Sun Jun 4 14:16:00 2017 Return-Path: Delivered-To: freebsd-current@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 0A8DFB7C73A for ; Sun, 4 Jun 2017 14:16:00 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from zxy.spb.ru (zxy.spb.ru [195.70.199.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id BC2B37777F; Sun, 4 Jun 2017 14:15:59 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from slw by zxy.spb.ru with local (Exim 4.86 (FreeBSD)) (envelope-from ) id 1dHWJp-000Gzg-Ul; Sun, 04 Jun 2017 17:15:49 +0300 Date: Sun, 4 Jun 2017 17:15:49 +0300 From: Slawa Olhovchenkov To: Allan Jude Cc: freebsd-current@freebsd.org Subject: Re: Time to increase MAXPHYS? Message-ID: <20170604141549.GC3182@zxy.spb.ru> References: <0100015c6fc1167c-6e139920-60d9-4ce3-9f59-15520276aebb-000000@email.amazonses.com> <972dbd34-b5b3-c363-721e-c6e48806e2cd@elischer.org> <3719c729-9434-3121-cf52-393a4453d0b2@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3719c729-9434-3121-cf52-393a4453d0b2@freebsd.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: slw@zxy.spb.ru X-SA-Exim-Scanned: No (on zxy.spb.ru); SAEximRunCond expanded to false X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Jun 2017 14:16:00 -0000 On Sat, Jun 03, 2017 at 11:55:51PM -0400, Allan Jude wrote: > On 2017-06-03 22:35, Julian Elischer wrote: > > On 4/6/17 4:59 am, Colin Percival wrote: > >> On January 24, 1998, in what was later renumbered to SVN r32724, dyson@ > >> wrote: > >>> Add better support for larger I/O clusters, including larger physical > >>> I/O. The support is not mature yet, and some of the underlying > >>> implementation > >>> needs help. However, support does exist for IDE devices now. > >> and increased MAXPHYS from 64 kB to 128 kB. Is it time to increase it > >> again, > >> or do we need to wait at least two decades between changes? > >> > >> This is hurting performance on some systems; in particular, EC2 "io1" > >> disks > >> are optimized for 256 kB I/Os, EC2 "st1" (throughput optimized > >> spinning rust) > >> disks are optimized for 1 MB I/Os, and Amazon's NFS service (EFS) > >> recommends > >> using a maximum I/O size of 1 MB (and despite NFS not being *physical* > >> I/O it > >> seems to still be limited by MAXPHYS). > >> > > We increase it in freebsd 8 and 10.3 on our systems, Only good results. > > > > sys/sys/param.h:#define MAXPHYS (1024 * 1024) /* max raw I/O > > transfer size */ > > > > _______________________________________________ > > freebsd-current@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-current > > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" > > At some point Warner and I discussed how hard it might be to make this a > boot time tunable, so that big amd64 machines can have a larger value > without causing problems for smaller machines. > > ZFS supports a block size of 1mb, and doing I/Os in 128kb negates some > of the benefit. 16MB