From: Leon Romanovsky <leonro@xxxxxxxxxxxx>
The remove_keys() logic is performed as garbage collection task. Such
task is intended to be run when no other active processes are running.
The need_resched() will return TRUE if there are user tasks to be
activated in near future.
In such case, we don't execute remove_keys() and postpone
the garbage collection work to try to run in next cycle,
in order to free CPU resources to other tasks.
The possible pseudo-code to trigger such scenario:
1. Allocate a lot of MR to fill the cache above the limit.
2. Wait a small amount of time "to calm" the system.
3. Start CPU extensive operations on multi-node cluster.
4. Expect performance degradation during MR cache shrink operation.
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Signed-off-by: Eli Cohen <eli@xxxxxxxxxxxx>
---
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 54a15b5..45ce00e 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -381,7 +381,19 @@
}
}
} else if (ent->cur > 2 * ent->limit) {
- if (!someone_adding(cache) &&
+ /*
+ * The remove_keys() logic is performed as garbage collection
+ * task. Such task is intended to be run when no other active
+ * processes are running.
+ *
+ * The need_resched() will return TRUE if there are user tasks
+ * to be activated in near future.
+ *
+ * In such case, we don't execute remove_keys() and postpone
+ * the garbage collection work to try to run in next cycle,
+ * in order to free CPU resources to other tasks.
+ */
+ if (!need_resched() && !someone_adding(cache) &&
time_after(jiffies, cache->last_add + 300 * HZ)) {
remove_keys(dev, i, 1);
if (ent->cur > ent->limit)
--
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