回复: Question on io-wq
发件人: Zhang, Qiang
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
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
>#include
>#include
>+#include
>#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(>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, >>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(>done);
>err:
>+ cpuhp_state_remove_instance_nocalls(io_wq_online, >>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, >>cpuhp_node);
>+
> set_bit(IO_WQ_BIT_EXIT, >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, );
--- raw_spin_lock_irqsave(>pi_lock, flags);
>+ do_set_cpus_allowed(task, cpumask_of_node(worker->wqe->node));
>+ task->flags |= PF_NO_SETAFFINITY;
--- raw_spin_unlock_irqrestore(>pi_lock, flags);
task_rq_unlock(rq, task, );
>+ 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
回复: Question on io-wq
发件人: Jens Axboe
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
>#include
>#include
>+#include
>#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(>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, >>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(>done);
>err:
>+ cpuhp_state_remove_instance_nocalls(io_wq_online, >>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, >>cpuhp_node);
>+
> set_bit(IO_WQ_BIT_EXIT, >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;
>+ raw_spin_lock_irqsave(>pi_lock, flags);
>+ do_set_cpus_allowed(task, cpumask_of_node(worker->wqe->node));
>+ task->flags |= PF_NO_SETAFFINITY;
>+ raw_spin_unlock_irqrestore(>pi_lock, flags);
>+ 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
Re: Question on io-wq
On 10/22/20 8:05 PM, Hillf Danton wrote: > On Thu, 22 Oct 2020 08:08:09 -0600 Jens Axboe wrote: >> 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? > > CPU affinity is intact because of nothing to do on offline, and scheduler > will move the stray workers on to the correct NUMA node if any CPU goes > online, so it's a bit hard to see what is going to be tested. Test it yourself: - Boot with > 1 NUMA node - Start an io_uring, you now get 2 workers, each affinitized to a node - Now offline all CPUs in one node - Online one or more of the CPU in that same node The end result is that the worker on the node that was offlined now has a mask of the other node, plus the newly added CPU. So your last statement isn't correct, which is what the original reporter stated. -- Jens Axboe
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
#include
#include
+#include
#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(>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, >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(>done);
err:
+ cpuhp_state_remove_instance_nocalls(io_wq_online, >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, >cpuhp_node);
+
set_bit(IO_WQ_BIT_EXIT, >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;
+
+ raw_spin_lock_irqsave(>pi_lock, flags);
+ do_set_cpus_allowed(task, cpumask_of_node(worker->wqe->node));
+ task->flags |= PF_NO_SETAFFINITY;
+ raw_spin_unlock_irqrestore(>pi_lock, flags);
+ 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
Question on io-wq
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? Thanks Qiang
Question on io-wq
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? Thanks Qiang
