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Thu, 18 Jun 2026 03:54:58 +0000 (GMT) Received: from [9.123.5.233] (unknown [9.123.5.233]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 18 Jun 2026 03:54:58 +0000 (GMT) Message-ID: <93e61992-98e6-4517-ad10-3a37dee1658a@linux.ibm.com> Date: Thu, 18 Jun 2026 09:24:57 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 08/20] sched/fair: load balance only among preferred CPUs To: K Prateek Nayak , linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, yury.norov@gmail.com, iii@linux.ibm.com Cc: tglx@kernel.org, gregkh@linuxfoundation.org, pbonzini@redhat.com, seanjc@google.com, vschneid@redhat.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, mgorman@suse.de, bsegall@google.com, maddy@linux.ibm.com, srikar@linux.ibm.com, hdanton@sina.com, chleroy@kernel.org, vineeth@bitbyteword.org, frederic@kernel.org, arighi@nvidia.com, pauld@redhat.com, christian.loehle@arm.com, tj@kernel.org, tommaso.cucinotta@gmail.com, maz@kernel.org, rafael@kernel.org References: <20260617174139.155540-1-sshegde@linux.ibm.com> <20260617174139.155540-9-sshegde@linux.ibm.com> From: Shrikanth Hegde Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjE4MDAzMCBTYWx0ZWRfXylqEWK2lTp/8 sbqhti9/XU9QtjOeZtiRl9KSc2UeFzTYDw4w5B92Jd7N9OCkFL1PuIaDsXG67k2MIasOvxR4oOV FbG7f553te/CH4uaMeN9PDUJM9pNZxpobfaWZha4UYXcCfh4lm6vfhg3wmNO2D9MmJrVpmVR4kv MRKoX/qynjXOAqyArRej0B0HPZSDFFyk7k9rkcyrDef0DY4MioNgM/8++/BxMA0vi5JiTAgydn3 O3WuPD+NhKKP70GaJsJzJ0QqTWo2AjTBIREJ1wYrJCrWrRUL/a+3m64VDSzKzwaDPPGUlM3WLiO qUjKGRi5QUvv1qkXX2pIoTv32BVz/WH9+OuRJ4O9OR4lAOHMw80KihzwAq4R5YS/Szci0iV+3Fb AgsWkibILja70xOwpu42Wvslc2+PB75Lm9goT6FjJ4fBzucgfISLnOICJizczT3UZYHcuvSPpXk 0KYoLAE/mIk6kLD0Zog== X-Proofpoint-GUID: QpXTsJIYsWegP0rRV2l5lK71zyygWKsJ X-Proofpoint-Spam-Info: AW1haW4tMjYwNjE4MDAzMCBTYWx0ZWRfX8ol4bWhYD3Kw c4Zz1Y+mGuyIN9y0WzEqivb2RolzJVUNNp/azzeiX9+4VDxwyiHquP2U1lYMZg7auM8D/lFM4bS jCnOFm7Glvs1WpfNhR/WkoQ7fEiI52Q= X-Proofpoint-ORIG-GUID: ZX3cKFP9GhYMax7bY-cgsIXn6HiCr5Ez X-Authority-Analysis: v=2.4 cv=auGCzyZV c=1 sm=1 tr=0 ts=6a336c1d cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=JEiWCK3E64Pv31shC98A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-17_02,2026-06-17_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 impostorscore=0 spamscore=0 lowpriorityscore=0 adultscore=0 malwarescore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606180030 Hi Prateek, thanks for going through the patches. On 6/18/26 8:33 AM, K Prateek Nayak wrote: > Hello Shrikanth, > > On 6/17/2026 11:11 PM, Shrikanth Hegde wrote: >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index d78467ec6ee1..3f3c7f0ca489 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -13291,6 +13291,9 @@ static int sched_balance_rq(int this_cpu, struct rq *this_rq, >> >> cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask); >> >> + /* Spread load among preferred CPUs */ >> + cpumask_and(cpus, cpus, cpu_preferred_mask); > > Since "cpu_preferred_mask" is a subset of "cpu_active_mask", just: > > cpumask_and(cpus, sched_domain_span(sd), cpu_preferred_mask); > > is sufficient. We don't need that redundant cpumask_and() with > cpu_active_mask before. > Ack. >> + >> schedstat_inc(sd->lb_count[idle]); >> >> redo: >