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Wed, 7 Jan 2026 06:51:50 +0000 (GMT) From: Shrikanth Hegde To: mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org Cc: sshegde@linux.ibm.com, kprateek.nayak@amd.com, juri.lelli@redhat.com, vschneid@redhat.com, tglx@linutronix.de, dietmar.eggemann@arm.com, anna-maria@linutronix.de, frederic@kernel.org, wangyang.guo@intel.com Subject: [PATCH v3 2/3] sched/fair: Change likelyhood of nohz.nr_cpus Date: Wed, 7 Jan 2026 12:21:24 +0530 Message-ID: <20260107065125.669668-3-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260107065125.669668-1-sshegde@linux.ibm.com> References: <20260107065125.669668-1-sshegde@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: KSGaHDUSz4eZC_HscUWYaY3jQRnBC41P X-Authority-Analysis: v=2.4 cv=Jvf8bc4C c=1 sm=1 tr=0 ts=695e028c cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=gfQPMJu-hSpRr0ZdjbEA:9 X-Proofpoint-ORIG-GUID: KSGaHDUSz4eZC_HscUWYaY3jQRnBC41P X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTA3MDA0OSBTYWx0ZWRfXxv/sYFhUxvpS rUZZPSNkzOH2H0f9gWvhBAUvMipbdQYaKOzTs7Ajb42JHIYKPg2mWswQQYKfegiGPr5dgUqXzc4 Np4w36tWoogIe+9CPIr31AAW3YRoS3z2EMpzMitgRr3wpi20bLi0OuCGQIOHtrf5Vqwql2oxHLR Orn4h7tnc70yNNKDJQKMYg9scVXPNkBM9/T5OiZp7gpi0NVOc7VSJdLh224DwXsOH8Gw9T/lpND 2GLxWC0quAIf6R9UeIjGPdoTOX7tIhOLVdTwiLXIDBByM3D8U5MTLEf721Ge3RvF0K1dtcrxHYJ jP1qB6gD0RoImobPOt8RBrzc6UnWtMY88pHiQ24JZN62gyQUEm1d9VRJbQiAfoidQkcIpPzqMW6 sQ/FCKYHt1yTQv1j3XjJA/44k4jXf5c2n7nwnDKlNgfEtV7n1ix0f7upKf2AEEhC3LgnrEsVR5v CXSjxLSVwVZpDuJNo/A== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-06_03,2026-01-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 suspectscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 adultscore=0 spamscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601070049 Content-Type: text/plain; charset="utf-8" These days most of the system have multi cores. The likelyhood of at least one or more CPUs in nohz (idle state) is higher. Give accurate hint to the branch predictor. Signed-off-by: Shrikanth Hegde --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 17e4e8ac5fca..c03f963f6216 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -12464,9 +12464,9 @@ static void nohz_balancer_kick(struct rq *rq) =20 /* * None are in tickless mode and hence no need for NOHZ idle load - * balancing: + * balancing */ - if (likely(!atomic_read(&nohz.nr_cpus))) + if (unlikely(!atomic_read(&nohz.nr_cpus))) return; =20 if (rq->nr_running >=3D 2) { --=20 2.47.3