From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031782AbdD0Mhv (ORCPT ); Thu, 27 Apr 2017 08:37:51 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:56856 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1031426AbdD0Mho (ORCPT ); Thu, 27 Apr 2017 08:37:44 -0400 Date: Thu, 27 Apr 2017 05:37:39 -0700 From: "Paul E. McKenney" To: Mike Galbraith Cc: LKML Subject: Re: TREE_SRCU slows hotplug by factor ~16 Reply-To: paulmck@linux.vnet.ibm.com References: <1493221799.6176.5.camel@gmx.de> <1493228757.4132.2.camel@gmx.de> <20170426175544.GW3956@linux.vnet.ibm.com> <20170426175610.GA6491@linux.vnet.ibm.com> <1493230330.4132.4.camel@gmx.de> <1493264639.4154.10.camel@gmx.de> <20170427041136.GA3956@linux.vnet.ibm.com> <1493266556.4154.11.camel@gmx.de> <20170427053228.GA11107@linux.vnet.ibm.com> <1493271840.4154.25.camel@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1493271840.4154.25.camel@gmx.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 17042712-0052-0000-0000-000001E92CDD X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006982; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00853198; UDB=6.00421817; IPR=6.00632035; BA=6.00005315; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015205; XFM=3.00000014; UTC=2017-04-27 12:37:41 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17042712-0053-0000-0000-00005046F4C9 Message-Id: <20170427123739.GD3956@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-27_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1704270208 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 27, 2017 at 07:44:00AM +0200, Mike Galbraith wrote: > On Wed, 2017-04-26 at 22:32 -0700, Paul E. McKenney wrote: > > On Thu, Apr 27, 2017 at 06:15:56AM +0200, Mike Galbraith wrote: > > > On Wed, 2017-04-26 at 21:11 -0700, Paul E. McKenney wrote: > > > > > > > This is with srcutree.exp_holdoff set to 25*1000? > > > > > > Yup. > > > > And please see below for the trivial patch, just for confirmation. > > May I add your Tested-by? > > Sure. > > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > > index ccbe1fb84165..65f03bca5b32 100644 > > --- a/kernel/rcu/srcutree.c > > +++ b/kernel/rcu/srcutree.c > > @@ -39,7 +39,7 @@ > > > > #include "rcu.h" > > > > -ulong exp_holdoff = 50 * 1000; /* Holdoff (ns) for auto-expediting. */ > > +ulong exp_holdoff = 25 * 1000; /* Holdoff (ns) for auto-expediting. */ > > Yup, exactly what I did. Woo-hoo!!! I will beat up on this a bit and send a pull request to Ingo. And thank you very much for finding this, gathering the trace data (which was critically important to my figuring out what was going on), and for testing the patches! Thanx, Paul