From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751380AbeEVQEw (ORCPT ); Tue, 22 May 2018 12:04:52 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:60949 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751196AbeEVQEt (ORCPT ); Tue, 22 May 2018 12:04:49 -0400 Date: Tue, 22 May 2018 09:05:34 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: linux-kernel@vger.kernel.org Subject: Re: RCU branching for the v4.19 merge window Reply-To: paulmck@linux.vnet.ibm.com References: <20180517144044.GA6089@linux.vnet.ibm.com> <20180522112736.4b44ae3c@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180522112736.4b44ae3c@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18052216-0012-0000-0000-0000164A0853 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009066; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000261; SDB=6.01036074; UDB=6.00529992; IPR=6.00815202; MB=3.00021242; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-22 16:04:44 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18052216-0013-0000-0000-000052E328A1 Message-Id: <20180522160534.GT3803@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-22_05:,, 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 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805220178 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 22, 2018 at 11:27:36AM -0400, Steven Rostedt wrote: > On Thu, 17 May 2018 07:40:44 -0700 > "Paul E. McKenney" wrote: > > > Hello, Steve! > > > > Another year, another difficult-to-branch set of RCU commits. > > > > In happy contrast to last year, I can make some branches (SRCU, some > > of the torture commits, and a few miscellaneous commits), but I will > > likely end up with several short branches and one huge one. My thought > > is to keep the long branch, but email the patches out in a few separate > > serieses, with each depending on its predecessor. For example, one series > > from the big branch would be folding the ->gpnum and ->completed fields > > into a single ->gp_seq, which helps the RCU-flavor consolidation task. > > Another series suppresses some rare false-positive splats that have been > > plaguing me for more than a year. Yet another series within this huge > > branch applies and optimizes funnel locking for grace-period startup. > > > > The problem is that the conversion to ->gp_seq has a very large footprint, > > which of course generates lots of conflicts. I could of course collapse > > these commits into a single commit, but if I did that I would also defer > > to the merge window following v4.19 due to the resulting loss of bisection > > within that change. > > > > Any advice? > > > > The commits are for-mingo..rcu/dev in my -rcu tree. > > I don't see these branches (and I don't pull tags). You don't see them yet because I don't create them until after -rc1 time, which is a few weeks out. If you go far enough down from rcu/dev you will see branches (about 90 commits down from HEAD), but these branches are already in -tip for v4.18. > How bad are the conflicts? Or is it too late to respond to help (sorry, > was on vacation :-) The conflicts are already causing me substantial hassles when rebasing bug fixes back to the buggy commits, so the conflicts are non-trivial. Hence my reaching out to you, given your discomfort with last year's long-chain RCU submission. And you do have some time to respond. ;-) Thanx, Paul