From 61b4944018449003ac5f9757f4d125dce519cf51 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Thu, 31 Jul 2008 15:42:53 -0400 Subject: Btrfs: Fix streaming read performance with checksumming on Large streaming reads make for large bios, which means each entry on the list async work queues represents a large amount of data. IO congestion throttling on the device was kicking in before the async worker threads decided a single thread was busy and needed some help. The end result was that a streaming read would result in a single CPU running at 100% instead of balancing the work off to other CPUs. This patch also changes the pre-IO checksum lookup done by reads to work on a per-bio basis instead of a per-page. This results in many extra btree lookups on large streaming reads. Doing the checksum lookup right before bio submit allows us to reuse searches while processing adjacent offsets. Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index e826730d750f..d2d1cc87e8ad 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1357,10 +1357,25 @@ struct btrfs_root *open_ctree(struct super_block *sb, */ btrfs_init_workers(&fs_info->workers, fs_info->thread_pool_size); btrfs_init_workers(&fs_info->submit_workers, fs_info->thread_pool_size); + + /* a higher idle thresh on the submit workers makes it much more + * likely that bios will be send down in a sane order to the + * devices + */ + fs_info->submit_workers.idle_thresh = 64; + btrfs_init_workers(&fs_info->fixup_workers, 1); btrfs_init_workers(&fs_info->endio_workers, fs_info->thread_pool_size); btrfs_init_workers(&fs_info->endio_write_workers, fs_info->thread_pool_size); + + /* + * endios are largely parallel and should have a very + * low idle thresh + */ + fs_info->endio_workers.idle_thresh = 4; + fs_info->endio_write_workers.idle_thresh = 4; + btrfs_start_workers(&fs_info->workers, 1); btrfs_start_workers(&fs_info->submit_workers, 1); btrfs_start_workers(&fs_info->fixup_workers, 1); -- cgit v1.2.3