Commit 23c671a5 authored by Miao Xie's avatar Miao Xie Committed by Chris Mason
Browse files

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: default avatarMiao Xie <>
Signed-off-by: default avatarJosef Bacik <>
Signed-off-by: default avatarChris Mason <>
parent 2c21b4d7
......@@ -3637,7 +3637,11 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
* 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);
ordered->csum_bytes_left == 0);
list_for_each_entry(sum, &ordered->list, list) {
ret = btrfs_csum_file_blocks(trans, log, sum);
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