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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 14 May 2019 23:13:33 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4EMDWRU17367060 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 May 2019 22:13:32 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D13A0B2073; Tue, 14 May 2019 22:13:32 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AD154B2071; Tue, 14 May 2019 22:13:32 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.216]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 14 May 2019 22:13:32 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 724DF16C3449; Tue, 14 May 2019 15:13:32 -0700 (PDT) Date: Tue, 14 May 2019 15:13:32 -0700 From: "Paul E. McKenney" To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org, Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Andrea Parri , Jonathan Corbet , linux-doc@vger.kernel.org Subject: Re: [PATCH] doc/rcu: Correct field_count field naming in examples Reply-To: paulmck@linux.ibm.com References: <20190505020328.165839-1-joel@joelfernandes.org> <20190507000453.GB3923@linux.ibm.com> <20190508162635.GD187505@google.com> <20190508181638.GY3923@linux.ibm.com> <20190513034305.GB96252@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190513034305.GB96252@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19051422-0072-0000-0000-0000042D0016 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011098; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000285; SDB=6.01203379; UDB=6.00631649; IPR=6.00984301; MB=3.00026893; MTD=3.00000008; XFM=3.00000015; UTC=2019-05-14 22:13:36 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19051422-0073-0000-0000-00004C390055 Message-Id: <20190514221332.GC4184@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-14_13:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905140146 Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Sun, May 12, 2019 at 11:43:05PM -0400, Joel Fernandes wrote: > On Wed, May 08, 2019 at 11:16:38AM -0700, Paul E. McKenney wrote: > [snip] > > > The other example could be dentry look up which uses seqlocks for the > > > RCU-walk case? But that could be too complex. This is also something I first > > > learnt from the paper and then the excellent path-lookup.rst document in > > > kernel sources. > > > > This is a great example, but it would need serious simplification for > > use in the Documentation/RCU directory. Note that dcache uses it to > > gain very limited and targeted consistency -- only a few types of updates > > acquire the write-side of that seqlock. > > > > Might be quite worthwhile to have a simplified example, though! > > Perhaps a trivial hash table where write-side sequence lock is acquired > > only when moving an element from one chain to another? > > Here you meant "moving from one chain to another" in the case of > hashtable-resizing right? I could not think of another reason why an element > is moved between 2 hash chains. Either that or in terms of atomic rekeying of a specific element in that table, thus potentially requiring an atomic move of only that specific element to another hash chain. > I just finished reading the main parts of Josh's relativistic hashtable paper > [1] and it is very cool indeed. The whole wait-for-readers application for > hashtable expansion is so well thought. I am planning to go over more papers > and code and can certainly update this example with a read-mostly hashtable > example as well as you are suggesting. :-) > > [1] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Sounds very good! Thanx, Paul