From d40f92020c7a225b77e68599e4b099a4a0823408 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 22 Apr 2024 14:43:48 -1000 Subject: [PATCH] workqueue: The default node_nr_active should have its max set to max_active The default nna (node_nr_active) is used when the pool isn't tied to a specific NUMA node. This can happen in the following cases: 1. On NUMA, if per-node pwq init failure and the fallback pwq is used. 2. On NUMA, if a pool is configured to span multiple nodes. 3. On single node setups. 5797b1c18919 ("workqueue: Implement system-wide nr_active enforcement for unbound workqueues") set the default nna->max to min_active because only #1 was being considered. For #2 and #3, using min_active means that the max concurrency in normal operation is pushed down to min_active which is currently 8, which can obviously lead to performance issues. exact value nna->max is set to doesn't really matter. #2 can only happen if the workqueue is intentionally configured to ignore NUMA boundaries and there's no good way to distribute max_active in this case. #3 is the default behavior on single node machines. Let's set it the default nna->max to max_active. This fixes the artificially lowered concurrency problem on single node machines and shouldn't hurt anything for other cases. Signed-off-by: Tejun Heo Reported-by: Shinichiro Kawasaki Fixes: 5797b1c18919 ("workqueue: Implement system-wide nr_active enforcement for unbound workqueues") Link: https://lore.kernel.org/dm-devel/20240410084531.2134621-1-shinichiro.kawasaki@wdc.com/ Signed-off-by: Tejun Heo --- kernel/workqueue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index a2af0aaf026b..5f536c63a48d 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1610,7 +1610,7 @@ static void wq_update_node_max_active(struct workqueue_struct *wq, int off_cpu) min_active, max_active); } - wq_node_nr_active(wq, NUMA_NO_NODE)->max = min_active; + wq_node_nr_active(wq, NUMA_NO_NODE)->max = max_active; } /**