From 23c671a58831a5aaca3b56b915c8394a274a96df Mon Sep 17 00:00:00 2001 From: Miao Xie Date: Tue, 14 Jan 2014 20:31:52 +0800 Subject: [PATCH] Btrfs: flush the dirty pages of the ordered extent aggressively during logging csum The performance of fsync dropped down suddenly sometimes, the main reason of this problem was that we might only flush part dirty pages in a ordered extent, then got that ordered extent, wait for the csum calcucation. But if no task flushed the left part, we would wait until the flusher flushed them, sometimes we need wait for several seconds, it made the performance drop down suddenly. (On my box, it drop down from 56MB/s to 4-10MB/s) This patch improves the above problem by flushing left dirty pages aggressively. Test Environment: CPU: 2CPU * 2Cores Memory: 4GB Partition: 20GB(HDD) Test Command: # sysbench --num-threads=8 --test=fileio --file-num=1 \ > --file-total-size=8G --file-block-size=32768 \ > --file-io-mode=sync --file-fsync-freq=100 \ > --file-fsync-end=no --max-requests=10000 \ > --file-test-mode=rndwr run Signed-off-by: Miao Xie Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/tree-log.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index b561e7a4007d..b142b6dc96c3 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -3637,7 +3637,11 @@ again: * start over after this. */ - wait_event(ordered->wait, ordered->csum_bytes_left == 0); + if (ordered->csum_bytes_left) { + btrfs_start_ordered_extent(inode, ordered, 0); + wait_event(ordered->wait, + ordered->csum_bytes_left == 0); + } list_for_each_entry(sum, &ordered->list, list) { ret = btrfs_csum_file_blocks(trans, log, sum);