If the cpumask is changed, it is possible that only a part of the per-node
pwq is affected. This can happen when the user changes the cpumask of
a workqueue or the low level cpumask.
So we try to reuse the current per-node pwq when its attrs are unchanged.
In wq_update_unbound_numa(), we had already made the current pwq be
reused when its attrs are unaffected, but we move the code of fetching
current pwq closer to the code of testing.
Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
---
kernel/workqueue.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 6aa9bd5..197520b 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3516,6 +3516,7 @@ apply_wqattrs_prepare(struct workqueue_struct *wq,
{
struct apply_wqattrs_ctx *ctx;
struct workqueue_attrs *new_attrs, *tmp_attrs;
+ struct pool_workqueue *pwq;
int node;
lockdep_assert_held(&wq_pool_mutex);
@@ -3556,9 +3557,16 @@ apply_wqattrs_prepare(struct workqueue_struct *wq,
for_each_node(node) {
if (wq_calc_node_cpumask(new_attrs, node, -1,
tmp_attrs->cpumask)) {
- ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
- if (!ctx->pwq_tbl[node])
- goto out_free;
+ /* Try to reuse the current one */
+ pwq = unbound_pwq_by_node(wq, node);
+ if (pwq && wqattrs_equal(tmp_attrs, pwq->pool->attrs)) {
+ get_pwq_unlocked(pwq);
+ } else {
+ pwq = alloc_unbound_pwq(wq, tmp_attrs);
+ if (!pwq)
+ goto out_free;
+ }
+ ctx->pwq_tbl[node] = pwq;
} else {
ctx->dfl_pwq->refcnt++;
ctx->pwq_tbl[node] = ctx->dfl_pwq;
@@ -3717,7 +3725,6 @@ static void wq_update_unbound_numa(struct
workqueue_struct *wq, int cpu,
cpumask = target_attrs->cpumask;
copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
- pwq = unbound_pwq_by_node(wq, node);
/*
* Let's determine what needs to be done. If the target cpumask is
@@ -3726,6 +3733,7 @@ static void wq_update_unbound_numa(struct
workqueue_struct *wq, int cpu,
* 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)) {
+ pwq = unbound_pwq_by_node(wq, node);
if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
return;
} else {
--
2.1.0
--
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