From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752977AbeBIWAo (ORCPT ); Fri, 9 Feb 2018 17:00:44 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:34870 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750993AbeBIWAn (ORCPT ); Fri, 9 Feb 2018 17:00:43 -0500 Subject: Re: [RESEND PATCH] sched/fair: consider RT/IRQ pressure in select_idle_sibling To: Dietmar Eggemann , Peter Zijlstra Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, steven.sistare@oracle.com, dhaval.giani@oracle.com, joelaf@google.com, vincent.guittot@linaro.org, morten.rasmussen@arm.com, eas-dev@lists.linaro.org References: <1517268429-933-1-git-send-email-rohit.k.jain@oracle.com> <20180209125358.GO25201@hirez.programming.kicks-ass.net> <2b3a903f-fbb6-cc0e-8a5d-e3329e1276c7@arm.com> From: Rohit Jain Message-ID: <14d6cf2f-b987-6987-0f9e-df03ba84d989@oracle.com> Date: Fri, 9 Feb 2018 14:05:17 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <2b3a903f-fbb6-cc0e-8a5d-e3329e1276c7@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8800 signatures=668666 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=739 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1802090277 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/09/2018 07:46 AM, Dietmar Eggemann wrote: > On 02/09/2018 01:53 PM, Peter Zijlstra wrote: >> On Mon, Jan 29, 2018 at 03:27:09PM -0800, Rohit Jain wrote: > > [...] > >>> @@ -6173,8 +6183,15 @@ static int select_idle_cpu(struct task_struct >>> *p, struct sched_domain *sd, int t >>>               return -1; >>>           if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) >>>               continue; >>> +        if (idle_cpu(cpu)) { >>> +            if (full_capacity(cpu)) { >>> +                best_cpu = cpu; >>> +                break; >>> +            } else if (capacity_of(cpu) > best_cap) { >>> +                best_cap = capacity_of(cpu); >>> +                best_cpu = cpu; >>> +            } >>> +        } >> >> No need for the else. And you'll note you're once again inconsistent >> with your previous self. >> >> But here I worry about big.little a wee bit. I think we're allowed big >> and little cores on the same L3 these days, and you can't directly >> compare capacity between them. >> >> Morten / Dietmar, any comments? > > Yes, for DynamIQ (big.little successor) systems, those cpus can have > different capacity_orig_of() values already. > OK, given that there are asymmetric capacities in L3 cores, we would probably have something like the below(?) in select_idle_cpu:           if (!cpumask_test_cpu(cpu, &p->cpus_allowed))               continue; +        if (idle_cpu(cpu) && !reduced_capacity(cpu)) +            break;