Btrfs: don't wait as long for more batches during SSD log commit

When we're doing log commits, we try to wait for more writers to come in
and make the commit bigger.  This helps improve performance on rotating
disks, but on SSDs it adds latencies.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 786639fca067992f75f546e4fc68bc3f2ac2e4fb..310ab22cfe58ff89160f1f2a708cfceb2d725771 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2013,10 +2013,10 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
        /* wait for previous tree log sync to complete */
        if (atomic_read(&root->log_commit[(index1 + 1) % 2]))
                wait_log_commit(trans, root, root->log_transid - 1);
-
        while (1) {
                unsigned long batch = root->log_batch;
-               if (root->log_multiple_pids) {
+               /* when we're on an ssd, just kick the log commit out */
+               if (!btrfs_test_opt(root, SSD) && root->log_multiple_pids) {
                        mutex_unlock(&root->log_mutex);
                        schedule_timeout_uninterruptible(1);
                        mutex_lock(&root->log_mutex);