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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 18 Jul 2019 11:08:20 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x6IA8Job38600810 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 18 Jul 2019 10:08:19 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CB82711C058; Thu, 18 Jul 2019 10:08:19 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8FECB11C054; Thu, 18 Jul 2019 10:08:17 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av25.portsmouth.uk.ibm.com (Postfix) with SMTP; Thu, 18 Jul 2019 10:08:17 +0000 (GMT) Date: Thu, 18 Jul 2019 15:38:16 +0530 From: Srikar Dronamraju To: subhra mazumdar Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, tglx@linutronix.de, prakash.sangappa@oracle.com, dhaval.giani@oracle.com, daniel.lezcano@linaro.org, vincent.guittot@linaro.org, viresh.kumar@linaro.org, tim.c.chen@linux.intel.com, mgorman@techsingularity.net Subject: Re: [RFC PATCH 3/3] sched: introduce tunables to control soft affinity Reply-To: Srikar Dronamraju References: <20190626224718.21973-1-subhra.mazumdar@oracle.com> <20190626224718.21973-4-subhra.mazumdar@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20190626224718.21973-4-subhra.mazumdar@oracle.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 x-cbid: 19071810-0012-0000-0000-00000334047E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19071810-0013-0000-0000-0000216D85F5 Message-Id: <20190718100816.GA19218@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-18_05:,, 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=8.0.1-1810050000 definitions=main-1907180113 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * subhra mazumdar [2019-06-26 15:47:18]: > For different workloads the optimal "softness" of soft affinity can be > different. Introduce tunables sched_allowed and sched_preferred that can > be tuned via /proc. This allows to chose at what utilization difference > the scheduler will chose cpus_allowed over cpus_preferred in the first > level of search. Depending on the extent of data sharing, cache coherency > overhead of the system etc. the optimal point may vary. > > Signed-off-by: subhra mazumdar > --- Correct me but this patchset only seems to be concentrated on the wakeup path, I don't see any changes in the regular load balancer or the numa-balancer. If system is loaded or tasks are CPU intensive, then wouldn't these tasks be moved to cpus_allowed instead of cpus_preferred and hence breaking this soft affinity. -- Thanks and Regards Srikar Dronamraju