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Fri, 2 Jan 2026 12:47:55 +0000 (GMT) From: Shrikanth Hegde To: mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org Cc: sshegde@linux.ibm.com, linux-kernel@vger.kernel.org, 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 v2 2/3] sched/fair: Change likelyhood of nohz.nr_cpus and do stats update if its due Date: Fri, 2 Jan 2026 18:17:43 +0530 Message-ID: <20260102124744.360872-3-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260102124744.360872-1-sshegde@linux.ibm.com> References: <20260102124744.360872-1-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: AW1haW4tMjYwMTAyMDExMyBTYWx0ZWRfX6POhJHEuY58Z pOhkhmnnRzeP1iIABjjZ/WLWuuLVANos/hQ+pgrz+rvzHp/hzY9oTdKvxBQEY3iT+zwFkpiOCHf EQC1EofIyMZzsqKpaLlWaU42Ql0sCLPiLPalRvBQUsezxdSxG5nbJB0V+wb68nkLXbj2n5Xlb2o S4M24FUlJFU7HsfyYOc1hv5/OreZM8CotMPdnje+6T/EqyOJBUBjoiyCfp6LwtzEuF9Pd82yYOT GzNsYfGh9N71bU87F4Sxpf4FaHct6iL8bgJ+pu80iEMS0LU4htQskm7iNEoIPvEGOYdfukiOWzg PkAEYSmJELW5tp7N+YHFCcigfnMtRewEM/BuIPRjpZ3YO/KHatVcPImsFWyRhB4N/gVMiYXa41g PrFMpedKm/jwgkQEPz9ht959xiBKJh2e1vLMqvoo+wg7K8zcgpy8Am6NLaApB9rhWjDGf6sRzT0 tdp8EvNwlfSuY/pR2Ew== X-Proofpoint-GUID: fh5I1w6DEDKnlf2b-mdHUTQzORvMCVrL X-Authority-Analysis: v=2.4 cv=B4+0EetM c=1 sm=1 tr=0 ts=6957be80 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=eJTnxkHzwNBm_rMR:21 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=L2DUigS4eapgOTKWHN4A:9 X-Proofpoint-ORIG-GUID: fh5I1w6DEDKnlf2b-mdHUTQzORvMCVrL 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=2026-01-02_01,2025-12-31_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 phishscore=0 bulkscore=0 clxscore=1015 malwarescore=0 impostorscore=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601020113 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. So move likely to unlikely. Allow stats balancing to complete when there are no nr_cpus as the check happens later. This may do an additional stats based load balancing which would reset has_blocked_load. Code also looks saner by removing that uncharactiristic return in between. Signed-off-by: Shrikanth Hegde --- kernel/sched/fair.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index cd1c78d2c272..5ceb9126d441 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -12456,10 +12456,10 @@ static void nohz_balancer_kick(struct rq *rq) =20 /* * None are in tickless mode and hence no need for NOHZ idle load - * balancing: + * balancing, do stats update if its due */ - if (likely(!atomic_read(&nohz.nr_cpus))) - return; + if (unlikely(!atomic_read(&nohz.nr_cpus))) + goto out; =20 if (rq->nr_running >=3D 2) { flags =3D NOHZ_STATS_KICK | NOHZ_BALANCE_KICK; --=20 2.47.3