On Thu, 06 Mar 2025, Bharata B Rao wrote:
+static int page_should_be_promoted(struct page_hotness_info *phi)
+{
+ struct page *page = pfn_to_online_page(phi->pfn);
+ unsigned long now = jiffies;
+ struct folio *folio;
+
+ if (!page || is_zone_device_page(page))
+ return false;
+
+ folio = page_folio(page);
+ if (!folio_test_lru(folio)) {
+ count_vm_event(KPROMOTED_MIG_NON_LRU);
+ return false;
+ }
+ if (folio_nid(folio) == phi->hot_node) {
+ count_vm_event(KPROMOTED_MIG_RIGHT_NODE);
+ return false;
+ }
How about using the LRU age itself:
if (folio_test_active())
return true;
+
+ /* If the page was hot a while ago, don't promote */
+ if ((now - phi->last_update) > 2 * msecs_to_jiffies(KPROMOTED_FREQ_WINDOW)) {
+ count_vm_event(KPROMOTED_MIG_COLD_OLD);
+ return false;
+ }
+
+ /* If the page hasn't been accessed enough number of times, don't promote */
+ if (phi->frequency < KPRMOTED_FREQ_THRESHOLD) {
+ count_vm_event(KPROMOTED_MIG_COLD_NOT_ACCESSED);
+ return false;
+ }
+ return true;
+}
...
+static int kpromoted(void *p)
+{
+ pg_data_t *pgdat = (pg_data_t *)p;
+ struct task_struct *tsk = current;
+ long timeout = msecs_to_jiffies(KPROMOTE_DELAY);
+
+ const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
+
+ if (!cpumask_empty(cpumask))
+ set_cpus_allowed_ptr(tsk, cpumask);
Explicit cpumasks are not needed if you use kthread_create_on_node().
See https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c6a566f6c1b4d5dff659acd221f95a72923f4085
+
+ while (!kthread_should_stop()) {
+ wait_event_timeout(pgdat->kpromoted_wait,
+ kpromoted_work_requested(pgdat), timeout);
+ kpromoted_do_work(pgdat);
+ }
+ return 0;
+}
+
+static void kpromoted_run(int nid)
+{
+ pg_data_t *pgdat = NODE_DATA(nid);
+
+ if (pgdat->kpromoted)
+ return;
+
+ pgdat->kpromoted = kthread_run(kpromoted, pgdat, "kpromoted%d", nid);
+ if (IS_ERR(pgdat->kpromoted)) {
+ pr_err("Failed to start kpromoted on node %d\n", nid);
+ pgdat->kpromoted = NULL;
+ }
+}
+
