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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 27 Jun 2018 18:26:29 -0400 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w5RMQSDq5243252 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 27 Jun 2018 22:26:29 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CF9A4B205F; Wed, 27 Jun 2018 18:26:20 -0400 (EDT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AA77DB2065; Wed, 27 Jun 2018 18:26:20 -0400 (EDT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.159]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 27 Jun 2018 18:26:20 -0400 (EDT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id EF64316C1222; Wed, 27 Jun 2018 15:28:35 -0700 (PDT) Date: Wed, 27 Jun 2018 15:28:35 -0700 From: "Paul E. McKenney" To: Linus Torvalds Cc: Ingo Molnar , "Eric W. Biederman" , Tejun Heo , Jann Horn , Benjamin LaHaise , Al Viro , Thomas Gleixner , Peter Zijlstra , Linux Kernel Mailing List Subject: Re: Simplifying our RCU models Reply-To: paulmck@linux.vnet.ibm.com References: <20180305082441.4hao2z4dqn2n5on6@gmail.com> <87po4izj67.fsf_-_@xmission.com> <20180305161446.GQ3918@linux.vnet.ibm.com> <20180306084738.tcs4ggbby77phlbh@gmail.com> <20180306203906.GA3918@linux.vnet.ibm.com> <20180307155444.GA10367@linux.vnet.ibm.com> <20180308204524.GW3918@linux.vnet.ibm.com> <20180410234425.GA30784@linux.vnet.ibm.com> <20180608165134.GA28693@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180608165134.GA28693@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18062722-0072-0000-0000-0000037625B3 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009266; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000266; SDB=6.01053254; UDB=6.00540020; IPR=6.00831178; MB=3.00021891; MTD=3.00000008; XFM=3.00000015; UTC=2018-06-27 22:26:33 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18062722-0073-0000-0000-00004882D3D6 Message-Id: <20180627222835.GA9656@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-27_07:,, 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=8.0.1-1806210000 definitions=main-1806270235 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 08, 2018 at 09:51:34AM -0700, Paul E. McKenney wrote: > On Tue, Apr 10, 2018 at 04:44:25PM -0700, Paul E. McKenney wrote: > > On Thu, Mar 08, 2018 at 12:45:24PM -0800, Paul E. McKenney wrote: > > > On Wed, Mar 07, 2018 at 10:48:50AM -0800, Linus Torvalds wrote: > > > > On Wed, Mar 7, 2018 at 7:54 AM, Paul E. McKenney > > > > wrote: > > > > > > > > > > Ah, and any thoughts on how best to get feedback from the various people > > > > > who would need to reprogram their fingers? Or is everyone already on > > > > > board with changing these various names? > > > > > > > > I really would prefer to not see massive re-naming unless there is a > > > > really good reason for it. > > > > > > > > I'm all for simplifying RCU from a million different versions down to > > > > just a few thousand, but I'm definitely not convinced we want to do > > > > any search-and-replace. > > > > > > I am currently in the design (more accurately, reredesign phase) for > > > the simplification. It is quite possible that there is a good reason > > > for at least some renaming, but in that case, I would come back later > > > with that as a separate proposal. > > > > And I really am still working on this. It is a bit tricky, but still > > looks doable. More likely to be ready for 4.19 than 4.18, though. > > I suppose it is well past time for an update... > > I believe I have the preparation work done (famous last words!), and I am > now working on making rcutorture properly test the resulting compound RCU > read-side critical sections. User-level testing might be necessary (and > has been for some of the preparatory work). The ink-on-paper prototype > is starting to look promising, and I expect to get the corresponding > prototype patch posted by the end of this month. > > A bit trickier than I expected (as usual), but still looking doable. And it now passes light rcutorture testing, so I have posted an RFC series to LKML: lkml.kernel.org/r/20180627204835.GA25456@linux.vnet.ibm.com There will be a long series of cleanups that will remove the other flavors and also the code that supports multiple flavors, but there are probably quite a few bugs to fix in this particular patch between now and then. ;-) Thanx, Paul