________________________________________
发件人: Zhang, Qiang <qiang.zh...@windriver.com>
发送时间: 2020年10月23日 11:55
收件人: Jens Axboe
抄送: v...@zeniv.linux.org.uk; io-ur...@vger.kernel.org;
linux-kernel@vger.kernel.org; linux-fsde...@vger.kernel.org
主题: 回复: Question on io-wq
________________________________________
发件人: Jens Axboe <ax...@kernel.dk>
发送时间: 2020年10月22日 22:08
收件人: Zhang, Qiang
抄送: v...@zeniv.linux.org.uk; io-ur...@vger.kernel.org;
linux-kernel@vger.kernel.org; linux-fsde...@vger.kernel.org
主题: Re: Question on io-wq
On 10/22/20 3:02 AM, Zhang,Qiang wrote:
>
> Hi Jens Axboe
>
> There are some problem in 'io_wqe_worker' thread, when the
> 'io_wqe_worker' be create and Setting the affinity of CPUs in NUMA
> nodes, due to CPU hotplug, When the last CPU going down, the
> 'io_wqe_worker' thread will run anywhere. when the CPU in the node goes
> online again, we should restore their cpu bindings?
>Something like the below should help in ensuring affinities are
>always correct - trigger an affinity set for an online CPU event. We
>should not need to do it for offlining. Can you test it?
>diff --git a/fs/io-wq.c b/fs/io-wq.c
>index 4012ff541b7b..3bf029d1170e 100644
>--- a/fs/io-wq.c
>+++ b/fs/io-wq.c
>@@ -19,6 +19,7 @@
>#include <linux/task_work.h>
>#include <linux/blk-cgroup.h>
>#include <linux/audit.h>
>+#include <linux/cpu.h>
>#include "io-wq.h"
>
>@@ -123,9 +124,13 @@ struct io_wq {
> refcount_t refs;
> struct completion done;
>
>+ struct hlist_node cpuhp_node;
>+
> refcount_t use_refs;
>};
>
>+static enum cpuhp_state io_wq_online;
>+
>static bool io_worker_get(struct io_worker *worker)
>{
> return refcount_inc_not_zero(&worker->ref);
>@@ -1096,6 +1101,13 @@ struct io_wq *io_wq_create(unsigned bounded, >struct
>io_wq_data *data)
> return ERR_PTR(-ENOMEM);
> }
>
>+ ret = cpuhp_state_add_instance_nocalls(io_wq_online, >&wq->cpuhp_node);
>+ if (ret) {
>+ kfree(wq->wqes);
>+ kfree(wq);
>+ return ERR_PTR(ret);
>+ }
>+
> wq->free_work = data->free_work;
> wq->do_work = data->do_work;
>
>@@ -1145,6 +1157,7 @@ struct io_wq *io_wq_create(unsigned bounded, >struct
>io_wq_data *data)
> ret = PTR_ERR(wq->manager);
> complete(&wq->done);
>err:
>+ cpuhp_state_remove_instance_nocalls(io_wq_online, >&wq->cpuhp_node);
> for_each_node(node)
> kfree(wq->wqes[node]);
> kfree(wq->wqes);
>@@ -1164,6 +1177,8 @@ static void __io_wq_destroy(struct io_wq *wq)
>{
> int node;
>
>+ cpuhp_state_remove_instance_nocalls(io_wq_online, >&wq->cpuhp_node);
>+
> set_bit(IO_WQ_BIT_EXIT, &wq->state);
> if (wq->manager)
> kthread_stop(wq->manager);
>@@ -1191,3 +1206,40 @@ struct task_struct *io_wq_get_task(struct io_wq >*wq)
>{
> return wq->manager;
>}
>+
>+static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
>+{
>+ struct task_struct *task = worker->task;
>+ unsigned long flags;
>+
struct rq_flags rf;
struct rq *rq;
rq = task_rq_lock(task, &rf);
--- raw_spin_lock_irqsave(&task->pi_lock, flags);
>+ do_set_cpus_allowed(task, cpumask_of_node(worker->wqe->node));
>+ task->flags |= PF_NO_SETAFFINITY;
--- raw_spin_unlock_irqrestore(&task->pi_lock, flags);
task_rq_unlock(rq, task, &rf);
>+ return false;
>+}
>+
>+static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
>+{
>+ struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
>+ int i;
>+
>+ rcu_read_lock();
>+ for_each_node(i)
>+ io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity,
>>NULL);
>+ rcu_read_unlock();
>+ return 0;
>+}
>+
>+static __init int io_wq_init(void)
>+{
>+ int ret;
>+
>+ ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, >"io->wq/online",
>+ io_wq_cpu_online, NULL);
>+ if (ret < 0)
>+ return ret;
>+ io_wq_online = ret;
>+ return 0;
>+}
>+subsys_initcall(io_wq_init);
>
>--
>Jens Axboe
