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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 20 Mar 2019 18:11:19 -0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2KIBKWf22347814 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Mar 2019 18:11:20 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 188FEB205F; Wed, 20 Mar 2019 18:11:20 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ED1A9B2067; Wed, 20 Mar 2019 18:11:19 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.188]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 20 Mar 2019 18:11:19 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 7D6A416C2A3C; Wed, 20 Mar 2019 11:12:10 -0700 (PDT) Date: Wed, 20 Mar 2019 11:12:10 -0700 From: "Paul E. McKenney" To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , tglx@linutronix.de, Mike Galbraith Subject: Re: [PATCH v2] rcu: Allow to eliminate softirq processing from rcutree Reply-To: paulmck@linux.ibm.com References: <20190318022434.GE4102@linux.ibm.com> <20190319114419.qlsw3i5bmndoyvao@linutronix.de> <20190320113219.d6c3gouqbnsnl5nj@linutronix.de> <20190320152146.GH4102@linux.ibm.com> <20190320154440.GA16332@linux.ibm.com> <20190320160547.s5lbeahr2y4jlzwt@linutronix.de> <20190320161500.GK4102@linux.ibm.com> <20190320163532.mr32oi53iaueuizw@linutronix.de> <20190320173001.GM4102@linux.ibm.com> <20190320175952.yh6yfy64vaiurszw@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190320175952.yh6yfy64vaiurszw@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19032018-0068-0000-0000-000003A8A138 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010789; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000281; SDB=6.01177176; UDB=6.00615785; IPR=6.00957872; MB=3.00026076; MTD=3.00000008; XFM=3.00000015; UTC=2019-03-20 18:11:21 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032018-0069-0000-0000-000047E1F443 Message-Id: <20190320181210.GO4102@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-20_10:,, 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=936 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903200133 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 20, 2019 at 06:59:52PM +0100, Sebastian Andrzej Siewior wrote: > On 2019-03-20 10:30:01 [-0700], Paul E. McKenney wrote: > > On Wed, Mar 20, 2019 at 05:35:32PM +0100, Sebastian Andrzej Siewior wrote: > > > On 2019-03-20 09:15:00 [-0700], Paul E. McKenney wrote: > > > > I am considering making it a module_param() to avoid namespace pollution, > > > > as it would become something like rcutree.nosoftirq. > > > > > > > > Thoughts? > > > > > > nope, perfect. > > > > Please see below for an untested patch. Thoughts? > > > - if (rcu_softirq_enabled) { > > + if (!nosoftirq) { > > raise_softirq(RCU_SOFTIRQ); > > } else { > > This double negation looks weird. Can we flip the logic somehow? > /me testing if it works… We could name it something like "use_softirq" and initialize it to true. I am OK either way. Thanx, Paul