From: SeongJae Park <sjpark@xxxxxxxxx>
As discussed by the previous commit ("xen/blkback: Aggressively shrink
page pools if a memory pressure is detected"), the aggressive pool
shrinking duration should be carefully selected:
``If it is too long, free pages pool shrinking overhead can reduce the
I/O performance. If it is too short, blkback will not free enough pages
to reduce the memory pressure.``
That said, the proper duration would depends on given configurations and
workloads. For the reason, this commit allows users to set it via a
module parameter interface.
Signed-off-by: SeongJae Park <sjpark@xxxxxxxxx>
Suggested-by: Amit Shah <aams@xxxxxxxxx>
---
drivers/block/xen-blkback/blkback.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index aa1a127093e5..88c011300ee9 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -137,9 +137,13 @@ module_param(log_stats, int, 0644);
/*
* Once a memory pressure is detected, keep aggressive shrinking of the free
- * page pools for this time (msec)
+ * page pools for this time (milliseconds)
*/
-#define AGGRESSIVE_SHRINKING_DURATION 1
+static int xen_blkif_aggressive_shrinking_duration = 1;
+module_param_named(aggressive_shrinking_duration,
+ xen_blkif_aggressive_shrinking_duration, int, 0644);
+MODULE_PARM_DESC(aggressive_shrinking_duration,
+"Duration to do aggressive shrinking when a memory pressure is detected");
static unsigned long xen_blk_mem_pressure_end;
@@ -147,7 +151,7 @@ static unsigned long blkif_shrink_count(struct shrinker *shrinker,
struct shrink_control *sc)
{
xen_blk_mem_pressure_end = jiffies +
- msecs_to_jiffies(AGGRESSIVE_SHRINKING_DURATION);
+ msecs_to_jiffies(xen_blkif_aggressive_shrinking_duration);
return 0;
}
--
2.17.1
