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Mon, 12 Jan 2026 05:05:03 +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@kernel.org, dietmar.eggemann@arm.com, anna-maria@linutronix.de, frederic@kernel.org, wangyang.guo@intel.com Subject: [PATCH v4 2/3] sched/fair: Change likelyhood of nohz.nr_cpus Date: Mon, 12 Jan 2026 10:34:41 +0530 Message-ID: <20260112050442.138446-3-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260112050442.138446-1-sshegde@linux.ibm.com> References: <20260112050442.138446-1-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-Spam-Details-Enc: AW1haW4tMjYwMTEyMDAzNyBTYWx0ZWRfX0Kk5PZTGI3ef 7kpoWUKigeKMV9oY3y13Gcdj8peoRoozPSOL/X5x2Kc6W/9UWfYrx7kR5sz8cswjkKmeQE2Rc/b X3oubBpjMBI715K5CpWu9/jRapYrHytVb3NWUHjWoQF2FBjP0Z+uI7pY3w1+0Pkg8b6pzzanBqP pNl0ufkERvTAgRrJmmW8uL9ce74RqvlY6oAKrq4ztdsd2Gb/Bsd03ZhB0tOckYQM742gzolNugs q2648o0l0nZm1lv03z8DiiQ+kZRsDtjjtSqlvVTTWRiMrGxR7H40nSPWM77iFF3H0LN1GNeNG3U jAtz9IeK37Jf4FZMjcibnv3YILJCmIT8XAszYKGo//RcH01sd2hP3jk4QyxYmTiZglqexKZueQs aHLY91mDNrR039jnFRCVbjTh3JnzXQWHUxJP3XBicn60yJum7te+PfJY1iiItZ4qIEQ5vJk+bQN Z537eYUK/1m0mzMdHpw== X-Proofpoint-ORIG-GUID: 6aV-MjFTPKLBvdg6p7e0exv5IA6SkXcd X-Authority-Analysis: v=2.4 cv=B/60EetM c=1 sm=1 tr=0 ts=69648105 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=gfQPMJu-hSpRr0ZdjbEA:9 X-Proofpoint-GUID: 6aV-MjFTPKLBvdg6p7e0exv5IA6SkXcd 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=2026-01-12_01,2026-01-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 bulkscore=0 spamscore=0 impostorscore=0 malwarescore=0 phishscore=0 adultscore=0 clxscore=1015 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601120037 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