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Thu, 15 Jan 2026 07:35:39 +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 v5 2/3] sched/fair: Change likelyhood of nohz.nr_cpus Date: Thu, 15 Jan 2026 13:05:23 +0530 Message-ID: <20260115073524.376643-3-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260115073524.376643-1-sshegde@linux.ibm.com> References: <20260115073524.376643-1-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: AW1haW4tMjYwMTE1MDA0NyBTYWx0ZWRfX7TVoPaN9edsZ 1VB+OT5nXYK4vlaquNkqirWo1DdgXN9SiZykzC2pOv9XlZRAKJn4S1k1ih2/DBoTuQ/FSVAd44D brsRf1zFYNQK++6KV9JPOIfbF6b6twLnRG5FXBVamGDO8As7h+gcvf48rVKj4ChmMb56Z0Lj/as zenxCpHpZu/268Vvv+pZDrXQyv8POXzJD7MI5YDFxiUHDNj3qTYPKZg+U1Vol9eNzNdoJtAJmGG 2/cAlE/ucmRMpx8qQaHGjutmpTn9nwNJyGJUBDbrInD78N79o4xtwOaXxCzBJQNx0OiUGZE8GJe 0juqn8IKRAWqXdyTPeVT412SJEYTa9QfwDrC54jjALX+BMEcQwRMBbo7ldGAMRxPaygYPlCUzXs JGMuCvuSPWwVlj3Wh6UBZm1fAR7uiIFVZVzkRSBiRqTN5CIUSqoecx9EBtgMJ0IgdCUsxaIPmqc HX/zQ9EfKCGcR9MFULA== X-Proofpoint-GUID: topDAAswqfAKt-YK-HSyzDHIkj18X2xb X-Authority-Analysis: v=2.4 cv=WLJyn3sR c=1 sm=1 tr=0 ts=696898d2 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=zd2uoN0lAAAA:8 a=VnNF1IyMAAAA:8 a=gfQPMJu-hSpRr0ZdjbEA:9 X-Proofpoint-ORIG-GUID: topDAAswqfAKt-YK-HSyzDHIkj18X2xb 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=2026-01-15_02,2026-01-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 malwarescore=0 phishscore=0 suspectscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601150047 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. Reviewed-and-tested-by: K Prateek Nayak 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 a4910658c5d6..3d843d1396ec 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -12463,9 +12463,9 @@ 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 2.51.0