From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751913AbeBYRvm (ORCPT ); Sun, 25 Feb 2018 12:51:42 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:39488 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751837AbeBYRvj (ORCPT ); Sun, 25 Feb 2018 12:51:39 -0500 Date: Sun, 25 Feb 2018 09:52:00 -0800 From: "Paul E. McKenney" To: Steven Rostedt Cc: Peter Zijlstra , 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, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com Subject: Re: [PATCH tip/core/rcu 10/10] rcu: Account for rcu_all_qs() in cond_resched() Reply-To: paulmck@linux.vnet.ibm.com References: <20171201192122.GA19301@linux.vnet.ibm.com> <1512156104-20104-10-git-send-email-paulmck@linux.vnet.ibm.com> <20171202085626.GS3326@worktop> <20171202122220.GM7829@linux.vnet.ibm.com> <20180224151816.45597ca1@vmware.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180224151816.45597ca1@vmware.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18022517-0052-0000-0000-000002BE21F8 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008596; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000254; SDB=6.00994971; UDB=6.00505700; IPR=6.00774305; MB=3.00019734; MTD=3.00000008; XFM=3.00000015; UTC=2018-02-25 17:51:37 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18022517-0053-0000-0000-00005BCF60A8 Message-Id: <20180225175200.GD2855@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-25_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 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802250238 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 24, 2018 at 03:18:16PM -0500, Steven Rostedt wrote: > On Sat, 2 Dec 2017 04:22:20 -0800 > "Paul E. McKenney" wrote: > > > Because there are a few key places within RCU and rcutorture that need it. > > Without it, there are scenarios where the new cond_resched() never gets > > activated, and thus doesn't take effect. > > > > The key point is that with this series in place, it should not be necessary > > to use cond_resched_rcu_qs() outside of kernel/rcu and kernel/torture.c. > > Which is a valuable step forward, right? > > I'm guessing the tracepoint benchmark is another situation. It's only > existence is to benchmark tracepoints and should not be enabled on any > production system. Thus, I think reverting patch 6 (the one removing it > from the benchmark code) is the proper solution. I would rather make the existing cond_resched() machinery work for RCU-tasks, but please let me know if my proposed fix isn't doing what you need. And in any case, please accept my apologies for the hassle! Thanx, Paul