diff mbox series

[RFC,13/20] mm: Make Kcompactd use kthread's preferred affinity

Message ID 20240726215701.19459-14-frederic@kernel.org (mailing list archive)
State New
Headers show
Series None | expand

Commit Message

Frederic Weisbecker July 26, 2024, 9:56 p.m. UTC 
Now that kthreads have an infrastructure to handle preferred affinity
against CPU hotplug and housekeeping cpumask, convert Kcompactd to use
it instead of handling halfway all the constraints by itself.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 mm/compaction.c | 43 +++----------------------------------------
 1 file changed, 3 insertions(+), 40 deletions(-)

Comments

Vlastimil Babka July 31, 2024, 3:03 p.m. UTC | #1 
On 7/26/24 11:56 PM, Frederic Weisbecker wrote:
> Now that kthreads have an infrastructure to handle preferred affinity
> against CPU hotplug and housekeeping cpumask, convert Kcompactd to use
> it instead of handling halfway all the constraints by itself.
> 
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>

Acked-by: Vlastimil Babka <vbabka@suse.cz>
diff mbox series

Patch

diff --git a/mm/compaction.c b/mm/compaction.c
index 739b1bf3d637..64a6486f06e1 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -3179,15 +3179,9 @@  void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx)
 static int kcompactd(void *p)
 {
 	pg_data_t *pgdat = (pg_data_t *)p;
-	struct task_struct *tsk = current;
 	long default_timeout = msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC);
 	long timeout = default_timeout;
 
-	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
-
-	if (!cpumask_empty(cpumask))
-		set_cpus_allowed_ptr(tsk, cpumask);
-
 	set_freezable();
 
 	pgdat->kcompactd_max_order = 0;
@@ -3258,11 +3252,13 @@  void __meminit kcompactd_run(int nid)
 	if (pgdat->kcompactd)
 		return;
 
-	pgdat->kcompactd = kthread_run(kcompactd, pgdat, "kcompactd%d", nid);
+	pgdat->kcompactd = kthread_create(kcompactd, pgdat, "kcompactd%d", nid);
 	if (IS_ERR(pgdat->kcompactd)) {
 		pr_err("Failed to start kcompactd on node %d\n", nid);
 		pgdat->kcompactd = NULL;
 	}
+	kthread_affine_preferred(pgdat->kcompactd, cpumask_of_node(pgdat->node_id));
+	wake_up_process(pgdat->kcompactd);
 }
 
 /*
@@ -3279,30 +3275,6 @@  void __meminit kcompactd_stop(int nid)
 	}
 }
 
-/*
- * It's optimal to keep kcompactd on the same CPUs as their memory, but
- * not required for correctness. So if the last cpu in a node goes
- * away, we get changed to run anywhere: as the first one comes back,
- * restore their cpu bindings.
- */
-static int kcompactd_cpu_online(unsigned int cpu)
-{
-	int nid;
-
-	for_each_node_state(nid, N_MEMORY) {
-		pg_data_t *pgdat = NODE_DATA(nid);
-		const struct cpumask *mask;
-
-		mask = cpumask_of_node(pgdat->node_id);
-
-		if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
-			/* One of our CPUs online: restore mask */
-			if (pgdat->kcompactd)
-				set_cpus_allowed_ptr(pgdat->kcompactd, mask);
-	}
-	return 0;
-}
-
 static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table,
 		int write, void *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -3362,15 +3334,6 @@  static struct ctl_table vm_compaction[] = {
 static int __init kcompactd_init(void)
 {
 	int nid;
-	int ret;
-
-	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
-					"mm/compaction:online",
-					kcompactd_cpu_online, NULL);
-	if (ret < 0) {
-		pr_err("kcompactd: failed to register hotplug callbacks.\n");
-		return ret;
-	}
 
 	for_each_node_state(nid, N_MEMORY)
 		kcompactd_run(nid);