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Tue, 7 Apr 2026 19:20:47 +0000 (GMT) From: Shrikanth Hegde To: linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@linutronix.de, yury.norov@gmail.com, gregkh@linuxfoundation.org Cc: sshegde@linux.ibm.com, pbonzini@redhat.com, seanjc@google.com, kprateek.nayak@amd.com, vschneid@redhat.com, iii@linux.ibm.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, mgorman@suse.de, bsegall@google.com, maddy@linux.ibm.com, srikar@linux.ibm.com, hdanton@sina.com, chleroy@kernel.org, vineeth@bitbyteword.org, joelagnelf@nvidia.com Subject: [PATCH v2 08/17] sched/rt: Select a preferred CPU for wakeup and pulling rt task Date: Wed, 8 Apr 2026 00:49:41 +0530 Message-ID: <20260407191950.643549-9-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260407191950.643549-1-sshegde@linux.ibm.com> References: <20260407191950.643549-1-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: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: n1wdP2IjEcwfDuRVfz1V-gjnelYLZn_7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDA3MDE3NSBTYWx0ZWRfXx9jPwHhX7BUp kiUBTB/id5QExJwSRFYAGJqIjw/QJ3gObncO3dQpRHlcWMf0ryWSMDqLWTc1TUmhLjLFfn0su3S 3wAH6nTxsQ02Tr0lZvNiH+f5s2HFn7fMJhj/WvrOVcpdjCrC1aBo4YCHKnt0Jo1mNNttGA/G/tY 6CQD+NvamHCanDSzg8dSgHz5JqYXhiNEOO0gzWPgsD++RdtMxaRUacYqwBP0bBYqQXfLGgJf/K/ 6z9251b6i5Ah8tbtK8wMBvdR49OPHR02718ffGQtYlOaUvrp9lyqbNuCGZpLpq63rNBIY+ihlJg IMDPtnqc6jsVhnZVhwREFR1hF5EiolF6YCGwZ+YTqyDXnPB+0xfp3KvrYjdaJ4z6SeOYXFKXxw3 G1okr1sCtzkqmKt+Tl0cunTlm23PIjZePvjRO9dPSPTcJdL1oOTKOk5ZRzpFnBwJ1si3+IkaY/G GeFA4RGlA6u/Rss2Njw== X-Authority-Analysis: v=2.4 cv=Cfw4Irrl c=1 sm=1 tr=0 ts=69d55918 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=wXEVXGXn7PT5tqLe4hQA:9 X-Proofpoint-GUID: 0FiKFixtYzdiUdeOSeWnD3fQmr3zK7XL X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-07_04,2026-04-07_05,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 phishscore=0 clxscore=1015 adultscore=0 suspectscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 spamscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604070175 For RT class, - During wakeup choose a preferred CPU. - For push_rt framework, limit pushing to preferred CPUs - Pull the rt task only if CPU is preferred. Signed-off-by: Shrikanth Hegde --- kernel/sched/cpupri.c | 4 ++++ kernel/sched/rt.c | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c index 8f2237e8b484..3e3106690ff3 100644 --- a/kernel/sched/cpupri.c +++ b/kernel/sched/cpupri.c @@ -104,6 +104,10 @@ static inline int __cpupri_find(struct cpupri *cp, struct task_struct *p, cpumask_and(lowest_mask, &p->cpus_mask, vec->mask); cpumask_and(lowest_mask, lowest_mask, cpu_active_mask); +#ifdef CONFIG_PARAVIRT + cpumask_and(lowest_mask, lowest_mask, cpu_preferred_mask); +#endif + /* * We have to ensure that we have at least one bit * still set in the array, since the map could have diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index a48e86794913..0c8cc8555287 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2262,6 +2262,10 @@ static void pull_rt_task(struct rq *this_rq) if (likely(!rt_overload_count)) return; + /* No point in pulling the load, just to push it next tick again */ + if (!cpu_preferred(this_cpu)) + return; + /* * Match the barrier from rt_set_overloaded; this guarantees that if we * see overloaded we must also see the rto_mask bit. -- 2.47.3