From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com [66.111.4.27]) by dpdk.org (Postfix) with ESMTP id 439CA1B123; Fri, 2 Nov 2018 10:36:37 +0100 (CET) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id D6B1A220A4; Fri, 2 Nov 2018 05:36:36 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Fri, 02 Nov 2018 05:36:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=monjalon.net; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding:content-type; s=mesmtp; bh=Jxiew2EbqeV5UtgkjSZYkrSRdGWLD+IdxGGsVSExw3Q=; b=Gr4uG/QNUI1n LDil535MaphEXkyddy8oLcIyBiidi+XCNSvc4a5x00LWGOr8zGFYggG+ec4mD5nV KwOgQkVcxfVPRsZMI7fHVLEg2k+ouj/1GPzSQxA+wjn90F+CGKZG8erpCb+QWbUD U22k3yr7h+GQJm/jOASG0wN2y4a4XL8= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm1; bh=Jxiew2EbqeV5UtgkjSZYkrSRdGWLD+IdxGGsVSExw 3Q=; b=O9i3fgp7QLn9pR+JGnsS/W/dkqo/4v321jjYzyJdVLZeyHd35cUojeBLX lHNTqaS1NqDEYueM8wcdFr9j4Dhor9YsUNxlq973ZwZszXSD3bTG6dRbeiICvSuT vzZ6cx3MV3mANAoXlhAWveeGCgkezpWmY+vLhMdnGd8lZjkyX2PapkLmT7Hccooz +os8KY27gb/dSrRCN/bIlqY3SvqPJ5iyTxQbtHMGSJVXGBx+iRPlPiLydZRwuPWR dsKzDJQVnzmH3GWxC8hLcATKGJgJ/BJ4ydLp5wSO7g3XWdSQ2brOcF2ITeh7StHG 2sHkC09haiqGLfSRKqyxJSKqJ6AXw== X-ME-Sender: X-ME-Proxy: Received: from xps.localnet (184.203.134.77.rev.sfr.net [77.134.203.184]) by mail.messagingengine.com (Postfix) with ESMTPA id AC68CE40E6; Fri, 2 Nov 2018 05:36:34 -0400 (EDT) From: Thomas Monjalon To: "Gavin Hu (Arm Technology China)" , Honnappa Nagarahalli Cc: Stephen Hemminger , "dev@dpdk.org" , "olivier.matz@6wind.com" , "chaozhu@linux.vnet.ibm.com" , "bruce.richardson@intel.com" , "konstantin.ananyev@intel.com" , "jerin.jacob@caviumnetworks.com" , "stable@dpdk.org" , nd Date: Fri, 02 Nov 2018 10:36:33 +0100 Message-ID: <15443120.J8yKmjSJbt@xps> In-Reply-To: References: <1541066031-29125-1-git-send-email-gavin.hu@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [dpdk-dev] [PATCH v4 2/2] ring: move the atomic load of head above the loop X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 02 Nov 2018 09:36:37 -0000 02/11/2018 08:15, Gavin Hu (Arm Technology China): > > > -----Original Message----- > > From: Honnappa Nagarahalli > > Sent: Friday, November 2, 2018 12:31 PM > > To: Gavin Hu (Arm Technology China) ; Stephen > > Hemminger > > Cc: dev@dpdk.org; thomas@monjalon.net; olivier.matz@6wind.com; > > chaozhu@linux.vnet.ibm.com; bruce.richardson@intel.com; > > konstantin.ananyev@intel.com; jerin.jacob@caviumnetworks.com; > > stable@dpdk.org; nd > > Subject: RE: [PATCH v4 2/2] ring: move the atomic load of head above the > > loop > > > > > > > > > > On Thu, 1 Nov 2018 17:53:51 +0800 > > Gavin Hu wrote: > > > > > +* **Updated the ring library with C11 memory model.** > > > + > > > + Updated the ring library with C11 memory model including the following > > changes: > > > + > > > + * Synchronize the load and store of the tail > > > + * Move the atomic load of head above the loop > > > + > > > > Does this really need to be in the release notes? Is it a user visible change or > > just an internal/optimization and fix. > > > > [Gavin] There is no api changes, but this is a significant change as ring is > > fundamental and widely used, it decreases latency by 25% in our tests, it may > > do even better for cases with more contending producers/consumers or > > deeper depth of rings. > > > > [Honnappa] I agree with Stephen. Release notes should be written from > > DPDK user perspective. In the rte_ring case, the user has the option of > > choosing between c11 and non-c11 algorithms. Performance would be one > > of the criteria to choose between these 2 algorithms. IMO, it probably makes > > sense to indicate that the performance of c11 based algorithm has been > > improved. However, I do not know what DPDK has followed historically > > regarding performance optimizations. I would prefer to follow whatever has > > been followed so far. > > I do not think that we need to document the details of the internal changes > > since it does not help the user make a decision. > > I read through the online guidelines for release notes, besides API and new features, resolved issues which are significant and not newly introduced in this release cycle, should also be included. > In this case, the resolved issue existed for long time, across multiple release cycles and ring is a core lib, so it should be a candidate for release notes. > > https://doc.dpdk.org/guides-18.08/contributing/patches.html > section 5.5 says: > Important changes will require an addition to the release notes in doc/guides/rel_notes/. > See the Release Notes section of the Documentation Guidelines for details. > https://doc.dpdk.org/guides-18.08/contributing/documentation.html#doc-guidelines > "Developers should include updates to the Release Notes with patch sets that relate to any of the following sections: > New Features > Resolved Issues (see below) > Known Issues > API Changes > ABI Changes > Shared Library Versions > Resolved Issues should only include issues from previous releases that have been resolved in the current release. Issues that are introduced and then fixed within a release cycle do not have to be included here." > > Suggested order in release notes items: > * Core libs (EAL, mempool, ring, mbuf, buses) > * Device abstraction libs and PMDs I agree with Honnappa. You don't need to give details, but can explain that performance of C11 version is improved.