ZEN: Tune mgLRU to protect cache used in the last second

damentz · damentz · commit 0696726eaf6d · 2022-01-16T09:52:34.000-06:00
Although not identical to the le9 patches that protect a byte-amount of cache through tunables, multigenerational LRU now supports protecting cache accessed in the last X milliseconds. In torvalds#218, Yu recommends starting with 1000ms and tuning as needed. This looks like a safe default and turning on this feature should help users that don't know they need it.
diff --git a/mm/vmscan.c b/mm/vmscan.c
@@ -4299,7 +4299,11 @@ static bool age_lruvec(struct lruvec *lruvec, struct scan_control *sc,
 }
 
 /* to protect the working set of the last N jiffies */
+#ifdef CONFIG_ZEN_INTERACTIVE
+static unsigned long lru_gen_min_ttl = HZ;
+#else
 static unsigned long lru_gen_min_ttl __read_mostly;
+#endif
 
 static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
 {

Original file line number	Diff line number	Diff line change
`@@ -4299,7 +4299,11 @@ static bool age_lruvec(struct lruvec lruvec, struct scan_control sc,`
`4299`	`4299`	`}`
`4300`	`4300`
`4301`	`4301`	`/* to protect the working set of the last N jiffies */`
	`4302`	`+#ifdef CONFIG_ZEN_INTERACTIVE`
	`4303`	`+static unsigned long lru_gen_min_ttl = HZ;`
	`4304`	`+#else`
`4302`	`4305`	`static unsigned long lru_gen_min_ttl __read_mostly;`
	`4306`	`+#endif`
`4303`	`4307`
`4304`	`4308`	`static void lru_gen_age_node(struct pglist_data pgdat, struct scan_control sc)`
`4305`	`4309`	`{`