From 6f3577bdc768e6dae3c4d419e89b5a904f470728 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Thu, 13 Nov 2008 09:59:36 -0500 Subject: Btrfs: Improve metadata read latencies This fixes latency problems on metadata reads by making sure they don't go through the async submit queue, and by tuning down the amount of readahead done during btree searches. Also, the btrfs bdi congestion function is tuned to ignore the number of pending async bios and checksums pending. There is additional code that throttles new async bios now and the congestion function doesn't need to worry about it anymore. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 8 ++++---- fs/btrfs/disk-io.c | 6 +++--- 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index f82f8db0227..ac61c50a331 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1285,16 +1285,16 @@ static noinline void reada_for_search(struct btrfs_root *root, } search = btrfs_node_blockptr(node, nr); if ((search >= lowest_read && search <= highest_read) || - (search < lowest_read && lowest_read - search <= 32768) || - (search > highest_read && search - highest_read <= 32768)) { + (search < lowest_read && lowest_read - search <= 16384) || + (search > highest_read && search - highest_read <= 16384)) { readahead_tree_block(root, search, blocksize, btrfs_node_ptr_generation(node, nr)); nread += blocksize; } nscan++; - if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32)) + if (path->reada < 2 && (nread > (64 * 1024) || nscan > 32)) break; - if(nread > (1024 * 1024) || nscan > 128) + if(nread > (256 * 1024) || nscan > 128) break; if (search < lowest_read) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 1bb54d69fbb..3b0e974a9e9 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -605,7 +605,7 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, BUG_ON(ret); return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, - mirror_num, 1); + mirror_num, 0); } return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info, inode, rw, bio, mirror_num, 0, @@ -1139,11 +1139,11 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits) struct list_head *cur; struct btrfs_device *device; struct backing_dev_info *bdi; - +#if 0 if ((bdi_bits & (1 << BDI_write_congested)) && btrfs_congested_async(info, 0)) return 1; - +#endif list_for_each(cur, &info->fs_devices->devices) { device = list_entry(cur, struct btrfs_device, dev_list); if (!device->bdev) -- cgit v1.2.3-70-g09d2