From owner-svn-src-head@freebsd.org Mon Dec 30 21:36:40 2019 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 46EC91EAE4B; Mon, 30 Dec 2019 21:36:40 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 47mrNR1Fssz4WLT; Mon, 30 Dec 2019 21:36:38 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (v-critter.freebsd.dk [192.168.55.3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by phk.freebsd.dk (Postfix) with ESMTPS id C70A21AF135; Mon, 30 Dec 2019 21:36:30 +0000 (UTC) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.15.2/8.15.2) with ESMTPS id xBULaU4Q027206 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 30 Dec 2019 21:36:30 GMT (envelope-from phk@critter.freebsd.dk) Received: (from phk@localhost) by critter.freebsd.dk (8.15.2/8.15.2/Submit) id xBULaToL027205; Mon, 30 Dec 2019 21:36:29 GMT (envelope-from phk) To: Warner Losh cc: Alexander Motin , Alexey Dokuchaev , src-committers , svn-src-all , svn-src-head Subject: Re: svn commit: r356185 - in head: lib/geom lib/geom/sched sys/geom sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/sys In-reply-to: From: "Poul-Henning Kamp" References: <201912292116.xBTLG4kV012809@repo.freebsd.org> <20191230113243.GA58338@FreeBSD.org> <20191230170208.GA20424@FreeBSD.org> <5a97d344-8741-3b8e-b6dd-b8e4cfa05aeb@FreeBSD.org> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-ID: <27203.1577741789.1@critter.freebsd.dk> Content-Transfer-Encoding: quoted-printable Date: Mon, 30 Dec 2019 21:36:29 +0000 Message-ID: <27204.1577741789@critter.freebsd.dk> X-Rspamd-Queue-Id: 47mrNR1Fssz4WLT X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of phk@critter.freebsd.dk designates 130.225.244.222 as permitted sender) smtp.mailfrom=phk@critter.freebsd.dk X-Spamd-Result: default: False [-1.86 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-0.98)[-0.980,0]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+mx]; NEURAL_HAM_LONG(-0.93)[-0.926,0]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[freebsd.dk]; RCPT_COUNT_FIVE(0.00)[6]; RCVD_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; IP_SCORE(0.05)[ip: (0.07), ipnet: 130.225.0.0/16(0.08), asn: 1835(0.10), country: EU(-0.00)]; FORGED_SENDER(0.30)[phk@phk.freebsd.dk,phk@critter.freebsd.dk]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:1835, ipnet:130.225.0.0/16, country:EU]; FROM_NEQ_ENVFROM(0.00)[phk@phk.freebsd.dk,phk@critter.freebsd.dk]; RCVD_TLS_ALL(0.00)[] X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Dec 2019 21:36:40 -0000 -------- In message , Warner Losh writes: >I never enabled it because I never had a good car size as the default. I'= m >guessing it's somewhere on the order of 2 times the queue size in >hardware, but with modern drives I think phk might be right and that >disabling disksort entirely might be optimal, or close to optimal. I think that is a given for SSDs. For disks I fear it would be a model-by-model determination. The situation is quite different for "traditional" and shingled drives for instance, or if, God forbid, the rumours are true and we'll see IBM3380-style dual head assemblies in the market again. I guess the kernel could turn the disksort on/off a few times and only leave it on if it improves things. But first, Somebody Should=E2=84=A2 benchmark to see if disksort *ever* is= an improvement on contemporary disks. Poul-Henning PS: If somebody really want to improve disk- and ssd- performance, the low-hanging fruit is to write a log-structured storage engine under UFS, to make life easier for flash-adaptation layers and shingling drives. -- = Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe = Never attribute to malice what can adequately be explained by incompetence= .