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Fri, 26 Jun 2026 13:35:15 +0000 (GMT) Received: from [9.39.23.71] (unknown [9.39.23.71]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 26 Jun 2026 13:35:15 +0000 (GMT) Message-ID: <82df9015-37db-429c-92ae-854cb2d4f5b7@linux.ibm.com> Date: Fri, 26 Jun 2026 19:05:14 +0530 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 09/24] sched/fair: Pull the load on preferred CPU To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, yury.norov@gmail.com, kprateek.nayak@amd.com, iii@linux.ibm.com, corbet@lwn.net, 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, 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, rdunlap@infradead.org, kernellwp@gmail.com, linux-doc@vger.kernel.org References: <20260625124648.802832-1-sshegde@linux.ibm.com> <20260625124648.802832-10-sshegde@linux.ibm.com> <20260626100043.GP1181229@noisy.programming.kicks-ass.net> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <20260626100043.GP1181229@noisy.programming.kicks-ass.net> 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-Authority-Analysis: v=2.4 cv=X4Ni7mTe c=1 sm=1 tr=0 ts=6a3e8020 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=J1G2in_c4E3h1slrROYA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwNjI2MDEwOSBTYWx0ZWRfX5I7G5NLuN/WG 42/v6J5h102nbU5pHMWtPih5macZOpGWdR1Qe6TZJvOdpmC6/0oONzsw50m+mjj66EgUeZ9hBjL JuFUTheFqa/pYWktWYZZkNS9wrtwrEA= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjI2MDEwOSBTYWx0ZWRfX7DsBvpR6b0dj cB/X3Wuac6VpCVyiHkkJcVpKTeJ4UwFREIgeAB/d83khsKojeGb5qUJyQUxEJUwhmm8swhH6Jn9 ZNJZBY3mo81FC3XxhGfWXMXZ5W7Xu+O2w1hdyHp6RsLGBR2tzmYuhy4pB89dd3z349LxfjwiQ2x 3sau/6M7toyc2FhYVjWGwraeZ0eqTdy0nhGc7mB+4+7Qx43ln3OoFlgt2OQ96RiDtBfJ69d6Rz6 nyFGRBAaJWFtVVLr9sHtNhZa+E4RlJJE7+JIbjirFUHDtJRJzyMRPqQdznpHp7K1VlBF87/uxxn IXrQLxiHshH1lBFaoMe27k4keBZjaMxnzGM4j3WWBIzfUZMhglngSm5NJJxyKXNFg7b44ZJjyZA SvgcCMsAqNCORb1xNoOJ+/c7mAQilMwnEr/DEC7Z8N9VSXkznyQC/NWtot8noL1iXZt6x4/xEdV 3SRUqUcXDNG0p7XPTHw== X-Proofpoint-ORIG-GUID: aY3ReeV2mBkdToo0pHfAlKQLyr7GAgpv X-Proofpoint-GUID: WSKpjBMzRyzeD_uIqs9GKnGPQ6tTF5Me 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=2026-06-26_03,2026-06-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 bulkscore=0 suspectscore=0 spamscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606260109 On 6/26/26 3:30 PM, Peter Zijlstra wrote: > On Thu, Jun 25, 2026 at 06:16:33PM +0530, Shrikanth Hegde wrote: > >> @@ -14375,6 +14379,10 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) >> if (!cpu_active(this_cpu)) >> return 0; >> >> + /* Do not pull to a !preferred CPU just to push it out next */ >> + if (!cpu_preferred(this_cpu)) >> + return 0; >> + >> /* >> * This is OK, because current is on_cpu, which avoids it being picked >> * for load-balance and preemption/IRQs are still disabled avoiding > > Why not just replace the cpu_active() check above? Ok. that should be fine. i will add a comment there.