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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 26 Jun 2018 16:38:29 -0400 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w5QKcSnR8913280 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 26 Jun 2018 20:38:28 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B4769B2066; Tue, 26 Jun 2018 16:38:21 -0400 (EDT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8D784B2068; Tue, 26 Jun 2018 16:38:21 -0400 (EDT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.159]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 26 Jun 2018 16:38:21 -0400 (EDT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id C3FAD16CA159; Tue, 26 Jun 2018 13:40:33 -0700 (PDT) Date: Tue, 26 Jun 2018 13:40:33 -0700 From: "Paul E. McKenney" To: Peter Zijlstra 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, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org Subject: Re: [PATCH tip/core/rcu 13/22] rcu: Fix grace-period hangs due to race with CPU offline Reply-To: paulmck@linux.vnet.ibm.com References: <20180626002052.GA24146@linux.vnet.ibm.com> <20180626171048.2181-13-paulmck@linux.vnet.ibm.com> <20180626174424.GK2494@hirez.programming.kicks-ass.net> <20180626181937.GG3593@linux.vnet.ibm.com> <20180626194807.GQ2494@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180626194807.GQ2494@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18062620-2213-0000-0000-000002C0595E X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009259; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000266; SDB=6.01052738; UDB=6.00539710; IPR=6.00830662; MB=3.00021868; MTD=3.00000008; XFM=3.00000015; UTC=2018-06-26 20:38:32 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18062620-2214-0000-0000-00005A9E2499 Message-Id: <20180626204033.GM3593@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-26_09:,, 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-1806260227 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 26, 2018 at 09:48:07PM +0200, Peter Zijlstra wrote: > On Tue, Jun 26, 2018 at 11:19:37AM -0700, Paul E. McKenney wrote: > > The initial reason for ____cacheline_internodealigned_in_smp was that > > some of the fields can be accessed by random CPUs, while others are > > used more locally, give or take our usual contention over the handling > > of CPU numbers. ;-) > > So that whole internode thing only matters for the insane VSMP case, > where they take node to mean a cluster node, not a numa node. > > VSMP is a networked shared memory machine where, by necessity, the MESI > protocol operates on page granularity. > > In general I tend to completely and utterly ignore that and let the VSMP > people worry about things. Sounds like I should queue a patch to replace them all with ____cacheline_aligned_in_smp. Any objections? (I don't consider this an emergency, so I would queue it for the merge window following the next one.) Thanx, Paul