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workqueue: Call wq_update_unbound_numa() on all CPUs in NUMA node on CPU hotplug 

When a CPU went online or offline, wq_update_unbound_numa() was called only
on the CPU which was going up or down. This works fine because all CPUs on
the same NUMA node share the same pool_workqueue slot - one CPU updating it
updates it for everyone in the node.

However, future changes will make each CPU use a separate pool_workqueue
even when they're sharing the same worker_pool, which requires updating
pool_workqueue's for all CPUs which may be sharing the same pool_workqueue
on hotplug.

To accommodate the planned changes, this patch updates
workqueue_on/offline_cpu() so that they call wq_update_unbound_numa() for
all CPUs sharing the same NUMA node as the CPU going up or down. In the
current code, the second+ calls would be noops and there shouldn't be any
behavior changes.

* As wq_update_unbound_numa() is now called on multiple CPUs per each
  hotplug event, @cpu is renamed to @hotplug_cpu and another @cpu argument
  is added. The former indicates the CPU being hot[un]plugged and the latter
  the CPU whose pool_workqueue is being updated.

* In wq_update_unbound_numa(), cpu_off is renamed to off_cpu for consistency
  with the new @hotplug_cpu.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2023-08-07 15:57:23 -10:00
parent 687a9aa56f
commit 4cbfd3de73
1 changed files with 25 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
kernel/workqueue.c
View File

@ -4422,7 +4422,8 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
/**
* wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
* @wq: the target workqueue
* @cpu: the CPU coming up or going down
* @cpu: the CPU to update pool association for
* @hotplug_cpu: the CPU coming up or going down
* @online: whether @cpu is coming up or going down
*
* This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
@ -4442,10 +4443,10 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
* CPU_DOWN_PREPARE.
*/
static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
bool online)
int hotplug_cpu, bool online)
{
int node = cpu_to_node(cpu);
int cpu_off = online ? -1 : cpu;
int off_cpu = online ? -1 : hotplug_cpu;
struct pool_workqueue *old_pwq = NULL, *pwq;
struct workqueue_attrs *target_attrs;
cpumask_t *cpumask;
@ -4473,7 +4474,7 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
* and create a new one if they don't match. If the target cpumask
* equals the default pwq's, the default pwq should be used.
*/
if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) {
if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, off_cpu, cpumask)) {
if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
return;
} else {
@ -5514,8 +5515,15 @@ int workqueue_online_cpu(unsigned int cpu)
}
/* update NUMA affinity of unbound workqueues */
list_for_each_entry(wq, &workqueues, list)
wq_update_unbound_numa(wq, cpu, true);
list_for_each_entry(wq, &workqueues, list) {
int tcpu;
for_each_possible_cpu(tcpu) {
if (cpu_to_node(tcpu) == cpu_to_node(cpu)) {
wq_update_unbound_numa(wq, tcpu, cpu, true);
}
}
}
mutex_unlock(&wq_pool_mutex);
return 0;
@ -5533,8 +5541,15 @@ int workqueue_offline_cpu(unsigned int cpu)
/* update NUMA affinity of unbound workqueues */
mutex_lock(&wq_pool_mutex);
list_for_each_entry(wq, &workqueues, list)
wq_update_unbound_numa(wq, cpu, false);
list_for_each_entry(wq, &workqueues, list) {
int tcpu;
for_each_possible_cpu(tcpu) {
if (cpu_to_node(tcpu) == cpu_to_node(cpu)) {
wq_update_unbound_numa(wq, tcpu, cpu, false);
}
}
}
mutex_unlock(&wq_pool_mutex);
return 0;
@ -6509,7 +6524,8 @@ void __init workqueue_init(void)
}
list_for_each_entry(wq, &workqueues, list) {
wq_update_unbound_numa(wq, smp_processor_id(), true);
wq_update_unbound_numa(wq, smp_processor_id(), smp_processor_id(),
true);
WARN(init_rescuer(wq),
"workqueue: failed to create early rescuer for %s",
wq->name);