FROMLIST: mm: compaction: fix wakeup logic of proactive compaction

Currently, proactive compaction tries to get triggered for every
HPAGE_FRAG_CHECK_INTERVAL_MSEC(=500msec) even when proactive compaction
is disabled with sysctl.compaction_proactiveness = 0. This results in
kcompactd thread wakes up and goes to sleep for every 500msec with out
the need of doing proactive compaction. Though this doesn't have any
overhead, few cpu cycles can be saved by avoid of waking up kcompactd
thread for proactive compaction when it is disabled.

Bug: 186387247
Link: https://lore.kernel.org/patchwork/patch/1438213/
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
Change-Id: I7e32dc0eec628df7d88d554dd325acfc9ac1ae57

mm/compaction.c

@@ -2868,11 +2868,14 @@ static int kcompactd(void *p)
 
 	while (!kthread_should_stop()) {
 		unsigned long pflags;
+		long timeout;
 
+		timeout = sysctl_compaction_proactiveness ?
+			msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC) :
+			MAX_SCHEDULE_TIMEOUT;
 		trace_mm_compaction_kcompactd_sleep(pgdat->node_id);
 		if (wait_event_freezable_timeout(pgdat->kcompactd_wait,
-			kcompactd_work_requested(pgdat),
-			msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC)) &&
+			kcompactd_work_requested(pgdat), timeout) &&
 			!pgdat->proactive_compact_trigger) {
 
 			psi_memstall_enter(&pflags);