From: wujing realwujing@gmail.com
We encountered an issue where the kernel thread `ksmd` runs on the PMD dedicated isolated core, leading to high latency in OVS packets.
Upon analysis, we discovered that this is caused by the current select_idle_smt() function not taking the sched_domain mask into account.
Kernel version: linux-4.19.y
Cc: stable@vger.kernel.org # 4.19.x Signed-off-by: wujing realwujing@qq.com Signed-off-by: QiLiang Yuan yuanql9@chinatelecom.cn --- kernel/sched/fair.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 09f82c84474b..0950cabfc1d0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6171,7 +6171,8 @@ static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int t return -1;
for_each_cpu(cpu, cpu_smt_mask(target)) { - if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) + if (!cpumask_test_cpu(cpu, &p->cpus_allowed) || + !cpumask_test_cpu(cpu, sched_domain_span(sd))) continue; if (available_idle_cpu(cpu)) return cpu;