Call balance_dirty_pages_ratelimit_nr() on every 16 pages dirtied. Experiments show that larger intervals (in the original code) can easily make the bdi dirty limit exceeded on 100 concurrent dd. CC: Chris Mason <chris.mason@xxxxxxxxxx> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> --- fs/btrfs/file.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- linux-next.orig/fs/btrfs/file.c 2010-12-09 12:24:59.000000000 +0800 +++ linux-next/fs/btrfs/file.c 2010-12-09 12:25:00.000000000 +0800 @@ -924,9 +924,8 @@ static ssize_t btrfs_file_aio_write(stru } iov_iter_init(&i, iov, nr_segs, count, num_written); - nrptrs = min((iov_iter_count(&i) + PAGE_CACHE_SIZE - 1) / - PAGE_CACHE_SIZE, PAGE_CACHE_SIZE / - (sizeof(struct page *))); + nrptrs = min(DIV_ROUND_UP(iov_iter_count(&i), PAGE_CACHE_SIZE), + min(16UL, PAGE_CACHE_SIZE / (sizeof(struct page *)))); pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL); /* generic_write_checks can change our pos */ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>