From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D34FBC433FF for ; Thu, 1 Aug 2019 23:16:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD99A206B8 for ; Thu, 1 Aug 2019 23:16:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732861AbfHAXQ0 (ORCPT ); Thu, 1 Aug 2019 19:16:26 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:15810 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728834AbfHAXQ0 (ORCPT ); Thu, 1 Aug 2019 19:16:26 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x71NDh4t012632 for ; Thu, 1 Aug 2019 19:16:24 -0400 Received: from e12.ny.us.ibm.com (e12.ny.us.ibm.com [129.33.205.202]) by mx0b-001b2d01.pphosted.com with ESMTP id 2u47v13a6y-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 01 Aug 2019 19:16:24 -0400 Received: from localhost by e12.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 2 Aug 2019 00:16:24 +0100 Received: from b01cxnp22035.gho.pok.ibm.com (9.57.198.25) by e12.ny.us.ibm.com (146.89.104.199) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 2 Aug 2019 00:16:19 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22035.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x71NGI0t52756870 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 1 Aug 2019 23:16:18 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B4F91B2064; Thu, 1 Aug 2019 23:16:18 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 967E9B205F; Thu, 1 Aug 2019 23:16:18 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.154]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 1 Aug 2019 23:16:18 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 011F416C9A39; Thu, 1 Aug 2019 16:16:19 -0700 (PDT) Date: Thu, 1 Aug 2019 16:16:19 -0700 From: "Paul E. McKenney" To: rcu@vger.kernel.org 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@joelfernandes.org Subject: [PATCH tip/core/rcu 0/10] No-CBs contention-reduction updates for v5.3-rc2 Reply-To: paulmck@linux.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19080123-0060-0000-0000-0000036772B6 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011535; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000287; SDB=6.01240747; UDB=6.00654302; IPR=6.01022171; MB=3.00028000; MTD=3.00000008; XFM=3.00000015; UTC=2019-08-01 23:16:23 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19080123-0061-0000-0000-00004A628E04 Message-Id: <20190801231619.GA22610@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-01_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=13 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=514 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908010245 Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Hello! This series partially addresses lock-contention increases caused by the move to the ->cblist segmented callback list. 1. Enable re-awakening under high callback load. 2. Never downgrade ->nocb_defer_wakeup in wake_nocb_gp_defer(). 3. Make __call_rcu_nocb_wake() safe for many callbacks. 4. Avoid needless wakeups of no-CBs grace-period kthread. 5. Avoid ->nocb_lock capture by corresponding CPU. 6. Round down for number of no-CBs grace-period kthreads. 7. Reduce contention at no-CBs registry-time CB advancement. 8. Reduce contention at no-CBs invocation-done time. 9. Reduce ->nocb_lock contention with separate ->nocb_gp_lock. 10. Unconditionally advance and wake for excessive CBs. Thanx, Paul ------------------------------------------------------------------------ tree.c | 20 ++++++++- tree.h | 21 ++++++++- tree_plugin.h | 128 ++++++++++++++++++++++++++++++++++++---------------------- 3 files changed, 118 insertions(+), 51 deletions(-)