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Message-Id: <20231227145143.2399-3-jiangshanlai@gmail.com>
Date: Wed, 27 Dec 2023 22:51:38 +0800
From: Lai Jiangshan <jiangshanlai@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>,
Naohiro.Aota@....com,
Lai Jiangshan <jiangshan.ljs@...group.com>,
Lai Jiangshan <jiangshanlai@...il.com>
Subject: [PATCH 2/7] workqueue: Share the same PWQ for the CPUs of a pod
From: Lai Jiangshan <jiangshan.ljs@...group.com>
PWQs with the same attrs shared the same pool. So just share the same
PWQ for all the CPUs of a pod instead of duplicating them.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
---
kernel/workqueue.c | 78 +++++++++++++++++++++++-----------------------
1 file changed, 39 insertions(+), 39 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e734625fc8ce..1f52685498f1 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4360,15 +4360,29 @@ apply_wqattrs_prepare(struct workqueue_struct *wq,
goto out_free;
for_each_possible_cpu(cpu) {
+ struct pool_workqueue *pwq;
+ int tcpu;
+
+ if (ctx->pwq_tbl[cpu])
+ continue;
wq_calc_pod_cpumask(new_attrs, cpu, -1);
if (cpumask_equal(new_attrs->cpumask, new_attrs->__pod_cpumask)) {
ctx->dfl_pwq->refcnt++;
ctx->pwq_tbl[cpu] = ctx->dfl_pwq;
continue;
}
- ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, new_attrs);
- if (!ctx->pwq_tbl[cpu])
+ pwq = alloc_unbound_pwq(wq, new_attrs);
+ if (!pwq)
goto out_free;
+ /*
+ * Reinitialize pwq->refcnt and prepare the new pwd for
+ * all the CPU of the pod.
+ */
+ pwq->refcnt = 0;
+ for_each_cpu(tcpu, new_attrs->__pod_cpumask) {
+ pwq->refcnt++;
+ ctx->pwq_tbl[tcpu] = pwq;
+ }
}
/* save the user configured attrs and sanitize it. */
@@ -4483,15 +4497,13 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
/**
* wq_update_pod - update pod affinity of a wq for CPU hot[un]plug
* @wq: the target workqueue
- * @cpu: the CPU to update pool association for
- * @hotplug_cpu: the CPU coming up or going down
+ * @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
* %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update pod affinity of
* @wq accordingly.
*
- *
* If pod affinity can't be adjusted due to memory allocation failure, it falls
* back to @wq->dfl_pwq which may not be optimal but is always correct.
*
@@ -4502,11 +4514,11 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
* CPU_DOWN. If a workqueue user wants strict affinity, it's the user's
* responsibility to flush the work item from CPU_DOWN_PREPARE.
*/
-static void wq_update_pod(struct workqueue_struct *wq, int cpu,
- int hotplug_cpu, bool online)
+static void wq_update_pod(struct workqueue_struct *wq, int cpu, bool online)
{
- int off_cpu = online ? -1 : hotplug_cpu;
- struct pool_workqueue *old_pwq = NULL, *pwq;
+ int off_cpu = online ? -1 : cpu;
+ int tcpu;
+ struct pool_workqueue *pwq;
struct workqueue_attrs *target_attrs;
lockdep_assert_held(&wq_pool_mutex);
@@ -4541,20 +4553,24 @@ static void wq_update_pod(struct workqueue_struct *wq, int cpu,
goto use_dfl_pwq;
}
- /* Install the new pwq. */
+ /* Install the new pwq for all the cpus of the pod */
mutex_lock(&wq->mutex);
- old_pwq = install_unbound_pwq(wq, cpu, pwq);
- goto out_unlock;
+ /* reinitialize pwq->refcnt before installing */
+ pwq->refcnt = 0;
+ for_each_cpu(tcpu, target_attrs->__pod_cpumask)
+ pwq->refcnt++;
+ for_each_cpu(tcpu, target_attrs->__pod_cpumask)
+ put_pwq_unlocked(install_unbound_pwq(wq, tcpu, pwq));
+ mutex_unlock(&wq->mutex);
+ return;
use_dfl_pwq:
mutex_lock(&wq->mutex);
raw_spin_lock_irq(&wq->dfl_pwq->pool->lock);
get_pwq(wq->dfl_pwq);
raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock);
- old_pwq = install_unbound_pwq(wq, cpu, wq->dfl_pwq);
-out_unlock:
+ put_pwq_unlocked(install_unbound_pwq(wq, cpu, wq->dfl_pwq));
mutex_unlock(&wq->mutex);
- put_pwq_unlocked(old_pwq);
}
static int alloc_and_link_pwqs(struct workqueue_struct *wq)
@@ -5563,15 +5579,8 @@ int workqueue_online_cpu(unsigned int cpu)
/* update pod affinity of unbound workqueues */
list_for_each_entry(wq, &workqueues, list) {
- struct workqueue_attrs *attrs = wq->unbound_attrs;
-
- if (attrs) {
- const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
- int tcpu;
-
- for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
- wq_update_pod(wq, tcpu, cpu, true);
- }
+ if (wq->unbound_attrs)
+ wq_update_pod(wq, cpu, true);
}
mutex_unlock(&wq_pool_mutex);
@@ -5591,15 +5600,8 @@ int workqueue_offline_cpu(unsigned int cpu)
/* update pod affinity of unbound workqueues */
mutex_lock(&wq_pool_mutex);
list_for_each_entry(wq, &workqueues, list) {
- struct workqueue_attrs *attrs = wq->unbound_attrs;
-
- if (attrs) {
- const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
- int tcpu;
-
- for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
- wq_update_pod(wq, tcpu, cpu, false);
- }
+ if (wq->unbound_attrs)
+ wq_update_pod(wq, cpu, false);
}
mutex_unlock(&wq_pool_mutex);
@@ -5891,9 +5893,8 @@ static int wq_affn_dfl_set(const char *val, const struct kernel_param *kp)
wq_affn_dfl = affn;
list_for_each_entry(wq, &workqueues, list) {
- for_each_online_cpu(cpu) {
- wq_update_pod(wq, cpu, cpu, true);
- }
+ for_each_online_cpu(cpu)
+ wq_update_pod(wq, cpu, true);
}
mutex_unlock(&wq_pool_mutex);
@@ -6803,9 +6804,8 @@ void __init workqueue_init_topology(void)
* combinations to apply per-pod sharing.
*/
list_for_each_entry(wq, &workqueues, list) {
- for_each_online_cpu(cpu) {
- wq_update_pod(wq, cpu, cpu, true);
- }
+ for_each_online_cpu(cpu)
+ wq_update_pod(wq, cpu, true);
}
mutex_unlock(&wq_pool_mutex);
--
2.19.1.6.gb485710b
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