From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 65ADE7D90D for ; Mon, 28 Oct 2019 18:02:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404294AbfJ1SCh (ORCPT ); Mon, 28 Oct 2019 14:02:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:42870 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730859AbfJ1SCg (ORCPT ); Mon, 28 Oct 2019 14:02:36 -0400 Received: from paulmck-ThinkPad-P72 (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 253A620862; Mon, 28 Oct 2019 18:02:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572285755; bh=Hyg++zfQSMX+47X9Z7dJD9TriyOsl/OxnbC82FMuQLA=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=qNfN5tlvR6Bc/HSOU2T5NwEH9tG876FuSY2Z9rzu8ckVYKZhUlhZZrUo7IRm8luG7 l0Q0zKiZWrYCqc1okeIwqoF0Sz28N1jbDTXgyTGrEUqW+h9PMDoTFT33gV0cByPup+ IsGWDrTlyxhOLYfdMgB19mVKHTo1nMBXgKCq8tT8= Date: Mon, 28 Oct 2019 11:02:33 -0700 From: "Paul E. McKenney" To: madhuparnabhowmik04@gmail.com Cc: joel@joelfernandes.org, corbet@lwn.net, linux-doc@vger.kernel.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Madhuparna Bhowmik Subject: Re: [PATCH 2/2] Documentation: RCU: Converted arrayRCU.txt to arrayRCU.rst. Message-ID: <20191028180233.GO4465@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20191028151936.27016-1-madhuparnabhowmik04@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191028151936.27016-1-madhuparnabhowmik04@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Mon, Oct 28, 2019 at 08:49:36PM +0530, madhuparnabhowmik04@gmail.com wrote: > From: Madhuparna Bhowmik > > This patch converts arrayRCU from txt to rst format. > arrayRCU.rst is also added in the index.rst file. > > Signed-off-by: Madhuparna Bhowmik > Signed-off-by: Madhuparna Bhowmik Thank you, but this does not apply to the -rcu git repo's "dev" branch. Could you please tell me what commit you developed this against? FYI, the location and much more about -rcu may be found here: https://mirrors.edge.kernel.org/pub/linux/kernel/people/paulmck/rcutodo.html Thanx, Paul > --- > .../RCU/{arrayRCU.txt => arrayRCU.rst} | 18 ++++++++++++++---- > Documentation/RCU/index.rst | 1 + > 2 files changed, 15 insertions(+), 4 deletions(-) > rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%) > > diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst > similarity index 91% > rename from Documentation/RCU/arrayRCU.txt > rename to Documentation/RCU/arrayRCU.rst > index f05a9afb2c39..c8a26f7b2577 100644 > --- a/Documentation/RCU/arrayRCU.txt > +++ b/Documentation/RCU/arrayRCU.rst > @@ -1,4 +1,7 @@ > +.. _array_rcu_doc: > + > Using RCU to Protect Read-Mostly Arrays > +======================================= > > > Although RCU is more commonly used to protect linked lists, it can > @@ -26,6 +29,7 @@ described in the following sections. > > > Situation 1: Hash Tables > +------------------------ > > Hash tables are often implemented as an array, where each array entry > has a linked-list hash chain. Each hash chain can be protected by RCU > @@ -34,6 +38,7 @@ to other array-of-list situations, such as radix trees. > > > Situation 2: Static Arrays > +-------------------------- > > Static arrays, where the data (rather than a pointer to the data) is > located in each array element, and where the array is never resized, > @@ -41,11 +46,14 @@ have not been used with RCU. Rik van Riel recommends using seqlock in > this situation, which would also have minimal read-side overhead as long > as updates are rare. > > -Quick Quiz: Why is it so important that updates be rare when > - using seqlock? > +Quick Quiz: > + Why is it so important that updates be rare when using seqlock? > + > +:ref:`Answer to Quick Quiz ` > > > Situation 3: Resizeable Arrays > +------------------------------ > > Use of RCU for resizeable arrays is demonstrated by the grow_ary() > function formerly used by the System V IPC code. The array is used > @@ -60,7 +68,7 @@ the remainder of the new, updates the ids->entries pointer to point to > the new array, and invokes ipc_rcu_putref() to free up the old array. > Note that rcu_assign_pointer() is used to update the ids->entries pointer, > which includes any memory barriers required on whatever architecture > -you are running on. > +you are running on.:: > > static int grow_ary(struct ipc_ids* ids, int newsize) > { > @@ -112,7 +120,7 @@ a simple check suffices. The pointer to the structure corresponding > to the desired IPC object is placed in "out", with NULL indicating > a non-existent entry. After acquiring "out->lock", the "out->deleted" > flag indicates whether the IPC object is in the process of being > -deleted, and, if not, the pointer is returned. > +deleted, and, if not, the pointer is returned.:: > > struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id) > { > @@ -144,8 +152,10 @@ deleted, and, if not, the pointer is returned. > return out; > } > > +.. _answer_quick_quiz_seqlock: > > Answer to Quick Quiz: > + Why is it so important that updates be rare when using seqlock? > > The reason that it is important that updates be rare when > using seqlock is that frequent updates can livelock readers. > diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst > index 340a9725676c..c4586602e7e2 100644 > --- a/Documentation/RCU/index.rst > +++ b/Documentation/RCU/index.rst > @@ -7,6 +7,7 @@ RCU concepts > .. toctree:: > :maxdepth: 1 > > + arrayRCU > rcu > listRCU > UP > -- > 2.17.1 >