[PATCH mm v5 RESEND 2/4] mm: move penalty delay clamping out of calculate_high_delay()

Jakub Kicinski
2020-05-21T00:24:18Z

We will want to call calculate_high_delay() twice - once for
memory and once for swap, and we should apply the clamp value
to sum of the penalties. Clamping has to be applied outside
of calculate_high_delay().

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
---
mm/memcontrol.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0d05e6a593f5..dd8605a9137a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2367,14 +2367,7 @@ static unsigned long calculate_high_delay(struct mem_cgroup *memcg,
* MEMCG_CHARGE_BATCH pages is nominal, so work out how much smaller or
* larger the current charge patch is than that.
*/
- penalty_jiffies = penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH;
-
- /*
- * Clamp the max delay per usermode return so as to still keep the
- * application moving forwards and also permit diagnostics, albeit
- * extremely slowly.
- */
- return min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES);
+ return penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH;
}

/*
@@ -2402,6 +2395,13 @@ void mem_cgroup_handle_over_high(void)
penalty_jiffies = calculate_high_delay(memcg, nr_pages,
mem_find_max_overage(memcg));

+ /*
+ * Clamp the max delay per usermode return so as to still keep the
+ * application moving forwards and also permit diagnostics, albeit
+ * extremely slowly.
+ */
+ penalty_jiffies = min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES);
+
/*
* Don't sleep if the amount of jiffies this memcg owes us is so low
* that it's not even worth doing, in an attempt to be nice to those who
--
2.25.4