From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932216AbeENQHq (ORCPT ); Mon, 14 May 2018 12:07:46 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:52482 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754627AbeENQHn (ORCPT ); Mon, 14 May 2018 12:07:43 -0400 Date: Mon, 14 May 2018 09:09:07 -0700 From: "Paul E. McKenney" To: Nicholas Piggin Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel.opensrc@gmail.com, torvalds@linux-foundation.org, npiggin@gmail.com Subject: Re: [PATCH tip/core/rcu 0/21] Contention reduction for v4.18 Reply-To: paulmck@linux.vnet.ibm.com References: <20180423030258.GA23370@linux.vnet.ibm.com> <20180514164233.7c7bff00@roar.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180514164233.7c7bff00@roar.ozlabs.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18051416-0008-0000-0000-000003074A16 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009024; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000260; SDB=6.01032235; UDB=6.00527695; IPR=6.00811366; MB=3.00021109; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-14 16:07:40 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18051416-0009-0000-0000-0000393F1C88 Message-Id: <20180514160907.GX26088@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-14_04:,, 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-1805140164 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 14, 2018 at 04:42:33PM +1000, Nicholas Piggin wrote: > On Sun, 22 Apr 2018 20:02:58 -0700 > "Paul E. McKenney" wrote: > > > Hello! > > > > This series reduces lock contention on the root rcu_node structure, > > and is also the first precursor to TBD changes to consolidate the > > three RCU flavors (RCU-bh, RCU-preempt, and RCU-sched) into one. > > Hi Paul, > > I've been running your rcu/dev branch and haven't noticed any problems > yet. The irqsoff latency improvement is a little hard to measure > because the scheduler, but I've tried turning balancing parameters > right down and I'm yet to see any sign of RCU in traces (down to about > 100us on a 176 CPU machine), so that's great. Good to hear!!! > (Not that RCU was ever the worst contributor to latency as I said, just > that I noticed those couple of traces where it showed up.) > > Thanks very much for the fast response, sorry I've taken a while to > test. Would you be willing to give me a Tested-by on that series of patches? Thanx, Paul