From f851689b5ae3eb8e1b4d397eaf2805ccfd88bf77 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Thu, 7 Sep 2017 11:22:20 -0600 Subject: Btrfs: remove nr_async_bios This was intended to congest higher layers to not send bios, but as 1) the congested bit has been taken by writeback Async bios come from buffered writes and DIO writes. For DIO writes, we want to submit them ASAP, while for buffered writes, writeback uses balance_dirty_pages() to throttle how much dirty pages we can have. 2) and no one is waiting for %nr_async_bios down to zero, Historically, it was introduced along with changes which let checksumming workload spread accross different cpus. And at that time, pdflush was used instead of per-bdi flushing, perhaps pdflush did not have the necessary information for writeback to do throttling. We can safely remove them now. Signed-off-by: Liu Bo [ additional explanation from mails, removed unused variable 'limit' ] Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 1 - 1 file changed, 1 deletion(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 09407384e996..2b18b0c379c1 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2518,7 +2518,6 @@ int open_ctree(struct super_block *sb, atomic_set(&fs_info->nr_async_submits, 0); atomic_set(&fs_info->async_delalloc_pages, 0); atomic_set(&fs_info->async_submit_draining, 0); - atomic_set(&fs_info->nr_async_bios, 0); atomic_set(&fs_info->defrag_running, 0); atomic_set(&fs_info->qgroup_op_seq, 0); atomic_set(&fs_info->reada_works_cnt, 0); -- cgit v1.2.3