When kswapd is awoken due to reclaim by a running task, set the priority of
kswapd to that of the calling task thus making memory reclaim cpu activity
affected by nice level.
Signed-off-by: Con Kolivas <[email protected]>
include/linux/mmzone.h | 2 +-
mm/page_alloc.c | 2 +-
mm/vmscan.c | 40 ++++++++++++++++++++++++++++++++++++++--
3 files changed, 40 insertions(+), 4 deletions(-)
Index: linux-ck-dev/include/linux/mmzone.h
===================================================================
--- linux-ck-dev.orig/include/linux/mmzone.h 2006-06-18 15:25:00.000000000 +1000
+++ linux-ck-dev/include/linux/mmzone.h 2006-06-18 15:25:02.000000000 +1000
@@ -330,7 +330,7 @@ void __get_zone_counts(unsigned long *ac
void get_zone_counts(unsigned long *active, unsigned long *inactive,
unsigned long *free);
void build_all_zonelists(void);
-void wakeup_kswapd(struct zone *zone, int order);
+void wakeup_kswapd(struct zone *zone, int order, struct task_struct *p);
int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
int classzone_idx, int alloc_flags);
Index: linux-ck-dev/mm/page_alloc.c
===================================================================
--- linux-ck-dev.orig/mm/page_alloc.c 2006-06-18 15:25:00.000000000 +1000
+++ linux-ck-dev/mm/page_alloc.c 2006-06-18 15:25:02.000000000 +1000
@@ -952,7 +952,7 @@ restart:
do {
if (cpuset_zone_allowed(*z, gfp_mask|__GFP_HARDWALL))
- wakeup_kswapd(*z, order);
+ wakeup_kswapd(*z, order, p);
} while (*(++z));
/*
Index: linux-ck-dev/mm/vmscan.c
===================================================================
--- linux-ck-dev.orig/mm/vmscan.c 2006-06-18 15:25:00.000000000 +1000
+++ linux-ck-dev/mm/vmscan.c 2006-06-18 15:25:02.000000000 +1000
@@ -897,6 +897,38 @@ static unsigned long shrink_zone(int pri
}
/*
+ * Helper functions to adjust nice level of kswapd, based on the priority of
+ * the task (p) that called it. If it is already higher priority we do not
+ * demote its nice level since it is still working on behalf of a higher
+ * priority task. With kernel threads we leave it at nice 0.
+ *
+ * We don't ever run kswapd real time, so if a real time task calls kswapd we
+ * set it to highest SCHED_NORMAL priority.
+ */
+static int effective_sc_prio(struct task_struct *p)
+{
+ if (likely(p->mm)) {
+ if (rt_task(p))
+ return -20;
+ return task_nice(p);
+ }
+ return 0;
+}
+
+static void set_kswapd_nice(task_t *kswapd, task_t *p, int active)
+{
+ long nice = effective_sc_prio(p);
+
+ if (task_nice(kswapd) > nice || !active)
+ set_user_nice(kswapd, nice);
+}
+
+static int sc_priority(struct task_struct *p)
+{
+ return (DEF_PRIORITY + (DEF_PRIORITY * effective_sc_prio(p) / 40));
+}
+
+/*
* This is the direct reclaim path, for page-allocating processes. We only
* try to reclaim pages from zones which will satisfy the caller's allocation
* request.
@@ -1266,6 +1298,7 @@ static int kswapd(void *p)
*/
order = new_order;
} else {
+ set_user_nice(tsk, 0);
schedule();
order = pgdat->kswapd_max_order;
}
@@ -1279,9 +1312,10 @@ static int kswapd(void *p)
/*
* A zone is low on free memory, so wake its kswapd task to service it.
*/
-void wakeup_kswapd(struct zone *zone, int order)
+void wakeup_kswapd(struct zone *zone, int order, struct task_struct *p)
{
pg_data_t *pgdat;
+ int active;
if (!populated_zone(zone))
return;
@@ -1293,7 +1327,9 @@ void wakeup_kswapd(struct zone *zone, in
pgdat->kswapd_max_order = order;
if (!cpuset_zone_allowed(zone, __GFP_HARDWALL))
return;
- if (!waitqueue_active(&pgdat->kswapd_wait))
+ active = waitqueue_active(&pgdat->kswapd_wait);
+ set_kswapd_nice(pgdat->kswapd, p, active);
+ if (!active)
return;
wake_up_interruptible(&pgdat->kswapd_wait);
}
--
-ck
-
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