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Tue, 27 May 2025 07:59:09 -0700 (PDT) Date: Tue, 27 May 2025 10:59:07 -0400 From: Yury Norov To: Shrikanth Hegde Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@linutronix.de, maddy@linux.ibm.com, vschneid@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, jstultz@google.com, kprateek.nayak@amd.com, huschle@linux.ibm.com, srikar@linux.ibm.com, linux-kernel@vger.kernel.org, linux@rasmusvillemoes.dk Subject: Re: [RFC PATCH 2/5] sched/core: Don't use parked cpu for selection Message-ID: References: <20250523181448.3777233-1-sshegde@linux.ibm.com> <20250523181448.3777233-3-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-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250523181448.3777233-3-sshegde@linux.ibm.com> On Fri, May 23, 2025 at 11:44:45PM +0530, Shrikanth Hegde wrote: > When the current running task is pushed using stop class mechanism, the > new CPU that going to be chosen shouldn't be a parked CPU. > > Signed-off-by: Shrikanth Hegde > --- > kernel/sched/core.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 62b3416f5e43..9ec12f9b3b08 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3526,7 +3526,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p) > nodemask = cpumask_of_node(nid); > > /* Look for allowed, online CPU in same node. */ > - for_each_cpu(dest_cpu, nodemask) { > + for_each_cpu_andnot(dest_cpu, nodemask, cpu_parked_mask) { > if (is_cpu_allowed(p, dest_cpu)) > return dest_cpu; > } > @@ -3534,7 +3534,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p) > > for (;;) { > /* Any allowed, online CPU? */ > - for_each_cpu(dest_cpu, p->cpus_ptr) { > + for_each_cpu_andnot(dest_cpu, p->cpus_ptr, cpu_parked_mask) { > if (!is_cpu_allowed(p, dest_cpu)) > continue; You test for online and dying CPUs in the is_cpu_allowed(). Why this new 'parked' creature is different?