From: Josef Bacik <josef@toxicpanda.com>
Date: Wed, 28 Apr 2021 13:38:43 -0400
Subject: btrfs: only clamp the first time we have to start flushing
Git-commit: 0aae4ca9e952b83f71ce50af1290f0f5d9ab9df6
Patch-mainline: v5.14-rc1
References: bsc#1202528
We were clamping the threshold for preemptive reclaim any time we added
a ticket to wait on, which if we have a lot of threads means we'd
essentially max out the clamp the first time we start to flush.
Instead of doing this, simply do it every time we have to start
flushing, this will make us ramp up gradually instead of going to max
clamping as soon as we start needing to do flushing.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
fs/btrfs/space-info.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index c9a5e003bcfa..33edab17af0d 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -1561,6 +1561,15 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info,
flush == BTRFS_RESERVE_FLUSH_DATA) {
list_add_tail(&ticket.list, &space_info->tickets);
if (!space_info->flush) {
+ /*
+ * We were forced to add a reserve ticket, so
+ * our preemptive flushing is unable to keep
+ * up. Clamp down on the threshold for the
+ * preemptive flushing in order to keep up with
+ * the workload.
+ */
+ maybe_clamp_preempt(fs_info, space_info);
+
space_info->flush = 1;
trace_btrfs_trigger_flush(fs_info,
space_info->flags,
@@ -1572,14 +1581,6 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info,
list_add_tail(&ticket.list,
&space_info->priority_tickets);
}
-
- /*
- * We were forced to add a reserve ticket, so our preemptive
- * flushing is unable to keep up. Clamp down on the threshold
- * for the preemptive flushing in order to keep up with the
- * workload.
- */
- maybe_clamp_preempt(fs_info, space_info);
} else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
used += orig_bytes;
/*