From owner-svn-src-all@freebsd.org Fri Mar 11 04:34:19 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 22CB6ACAAD3 for ; Fri, 11 Mar 2016 04:34:19 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-io0-x22e.google.com (mail-io0-x22e.google.com [IPv6:2607:f8b0:4001:c06::22e]) (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 DC11EAA5 for ; Fri, 11 Mar 2016 04:34:18 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-io0-x22e.google.com with SMTP id n190so132097895iof.0 for ; Thu, 10 Mar 2016 20:34:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc; bh=XsMrTumeyCBi5EyVsDY14Go3S8xsM6aNQOK/SML6KZw=; b=VFMwYHlpfAT+UWI1ZJqWt2s+F/tgFOsxKG5fiDA3wEj2kijYexClw91DLdixOw6dKv sYouzKajg83hbv+UHmXjnNM+W6j3QVn2kZI9rt8+PGCGrkz1bF4tdH57CTFHcHMg/N+D kqbM8jxDYzJhSsV708a7ZnE+pxUASOAXO8e5lJCQTsUMPpfsb2xOynhfkb+nruhSyxvt jSC8aieqwvMwq/+qMgFqSQ+5WOlVjzFoLuavih6aeF59DGN2Kvuo0mmSlSHGH3HmrvBJ QITaR4djF1MNzdlfY/MLUPnPOP59V83KUtE+pUlJ9xGI1QUANQv2RfniQNQ8CKVbXx8u zc5w== 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=XsMrTumeyCBi5EyVsDY14Go3S8xsM6aNQOK/SML6KZw=; b=V/cAFjZmaWRfKRE2obvt9k6BwxordLfs8wPKETrWjpuhlDvK/EYJwNto8d3obi5Owq xy8v0Lmam1nMvxYvxOshgrHWoPqFO1yjVJeXTKR84FThazG48N/8mBwqhpOSeRlhg8t+ iYOZGhmvYzhvOvpC4Zt2tiCfd1TkVaUvcWB6uoC3tHASGvYtTF5qb6pt6jyurDM3oJUn B4/LJc2P+OIeVholwkEz69bLbDpitr6Ac0R7IGDZpXsUm5GQyjIoZBTnlu+FwlpZpzgJ yvRt0E9O8RZsOetgVs8hAmLbTGEyGtjqDKloTBMc/qixBawJ5PPHYt9A7U1S4qo2yDbT pmKw== X-Gm-Message-State: AD7BkJIZ2xc9Zx/Bhn1oMeYp29SjN5szNbed7B529kwscnWCbn42JMGIKJK8/OgG3g0C26qbhxRuGAHyQwrYAA== MIME-Version: 1.0 X-Received: by 10.107.155.206 with SMTP id d197mr7019850ioe.135.1457670858192; Thu, 10 Mar 2016 20:34:18 -0800 (PST) Sender: wlosh@bsdimp.com Received: by 10.36.65.230 with HTTP; Thu, 10 Mar 2016 20:34:18 -0800 (PST) X-Originating-IP: [50.253.99.174] In-Reply-To: References: <201512110206.tBB264Ad039486@repo.freebsd.org> Date: Thu, 10 Mar 2016 21:34:18 -0700 X-Google-Sender-Auth: qUUu7jjXaR7l7PQYGU8QHA4MEd8 Message-ID: Subject: Re: svn commit: r292074 - in head/sys/dev: nvd nvme From: Warner Losh To: Alan Somers Cc: Steven Hartland , "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: Fri, 11 Mar 2016 04:34:19 -0000 Some Intel NVMe drives behave badly when the LBA range crosses a 128k boundary. Their performance is worse for those transactions than for ones that don't cross the 128k boundary. Warner On Thu, Mar 10, 2016 at 11:01 AM, Alan Somers wrote: > 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 >> >>