From owner-svn-src-all@freebsd.org Thu Mar 10 18:01:24 2016 Return-Path: Delivered-To: svn-src-all@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 B3288ACA3A8; Thu, 10 Mar 2016 18:01:24 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-oi0-x22c.google.com (mail-oi0-x22c.google.com [IPv6:2607:f8b0:4003:c06::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 78ED280; Thu, 10 Mar 2016 18:01:24 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-oi0-x22c.google.com with SMTP id c203so67210848oia.2; Thu, 10 Mar 2016 10:01:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc; bh=r06xt4xjceEb9+P5GF5WZC+eH8203WYr1nowd6viqjc=; b=z3LFtDnHUazeoFD08dNww5GEBEYJawNUBPkaBJ5eHn3jbgmpkM4oHUwnp5uhQcS7XP elMvCBfkWmXLVuc6uW2Y5d8bWGk2c8p+bxjhydcQi+Po5ztVCC0Mx8DUYf1u0j+Cz4hV jlL9udHA9Jk/Ms67+Ku8yxB4o7bkoxFgIID1f/llqsP0ESKdulMFFOuPg4V5fpVWvFjj 80uaC+C1akXB0tzXk7+pI119HF81663zeHS+xEjNHGc/zTfFyeSzdRoUz/alFtkZxzA6 cN5bUxzV+8ErDk8yP36HBvbSv2StZrL2egUr1FPTHQ/B98SPoGl9wrH9bafslUNmbmLb tlYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:date :message-id:subject:from:to:cc; bh=r06xt4xjceEb9+P5GF5WZC+eH8203WYr1nowd6viqjc=; b=l1dhlcOjla+oNPvXY+5SbQERr9Yhx8qaE4En0FsWOXBfk/dhPHgfb8xuf2bQqLneTd kvzD/3G7VO56y8maDnUMzeyyu3RKVX3TZC6p8syu6W4eCbK7SwAzcPmcyqUTN1JQQKhL WHUkp6EHjn9i1ydJ1VTkzV7lL1iIbzRrUlGON49p5WKgIs2/nHaovfomEq+u5WoQzhgC gWTOIu+UxzmBJBivN21p9UqZSDWSuiZ2VkQYSDe/3jC816CFe64B0z85DBugtcK139Ai buFPZHaPhWy52e0P1yYe+cfpWExMn6HbxYuIIuneLudF8p0AojVNs5JfIfKgZqbivceB PtRg== X-Gm-Message-State: AD7BkJJ9n17RYeyrm/qFt6148HusZXPV1PodY8bTmnKLb7O8/eQfPfin86bskmhNYG8BrzCv6tjffKQQY+uqdw== MIME-Version: 1.0 X-Received: by 10.202.202.87 with SMTP id a84mr2919921oig.57.1457632883764; Thu, 10 Mar 2016 10:01:23 -0800 (PST) Sender: asomers@gmail.com Received: by 10.202.64.138 with HTTP; Thu, 10 Mar 2016 10:01:23 -0800 (PST) In-Reply-To: <201512110206.tBB264Ad039486@repo.freebsd.org> References: <201512110206.tBB264Ad039486@repo.freebsd.org> Date: Thu, 10 Mar 2016 11:01:23 -0700 X-Google-Sender-Auth: NWfpbGy-Nwb8clal8s5I1OJFgjg Message-ID: Subject: Re: svn commit: r292074 - in head/sys/dev: nvd nvme From: Alan Somers To: Steven Hartland Cc: "src-committers@freebsd.org" , "svn-src-all@freebsd.org" , "svn-src-head@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.21 X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Mar 2016 18:01:24 -0000 Are you saying that Intel NVMe controllers perform poorly for all I/Os that are less than 128KB, or just for I/Os of any size that cross a 128KB boundary? On Thu, Dec 10, 2015 at 7:06 PM, Steven Hartland wrote: > Author: smh > Date: Fri Dec 11 02:06:03 2015 > New Revision: 292074 > URL: https://svnweb.freebsd.org/changeset/base/292074 > > Log: > Limit stripesize reported from nvd(4) to 4K > > Intel NVMe controllers have a slow path for I/Os that span a 128KB > stripe boundary but ZFS limits ashift, which is derived from d_stripesize, > to 13 (8KB) so we limit the stripesize reported to geom(8) to 4KB. > > This may result in a small number of additional I/Os to require > splitting in nvme(4), however the NVMe I/O path is very efficient so these > additional I/Os will cause very minimal (if any) difference in performance > or CPU utilisation. > > This can be controller by the new sysctl > kern.nvme.max_optimal_sectorsize. > > MFC after: 1 week > Sponsored by: Multiplay > Differential Revision: https://reviews.freebsd.org/D4446 > > Modified: > head/sys/dev/nvd/nvd.c > head/sys/dev/nvme/nvme.h > head/sys/dev/nvme/nvme_ns.c > head/sys/dev/nvme/nvme_sysctl.c > >