Hi This patch should be applied after dm-support-non-power-of-two-target-max_io_len.patch. It optimizes a case when max_io_len is a power of two. Mikulas --- dm: optimize modulo max_io_len Change slow modulo operation to fast bitwise and when max_io_len is a power of two. Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> --- drivers/md/dm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) Index: linux-3.4.2-fast/drivers/md/dm.c =================================================================== --- linux-3.4.2-fast.orig/drivers/md/dm.c 2012-06-18 11:40:17.000000000 +0200 +++ linux-3.4.2-fast/drivers/md/dm.c 2012-06-18 11:41:05.000000000 +0200 @@ -1004,7 +1004,11 @@ static sector_t max_io_len(sector_t sect */ if (ti->max_io_len) { offset = dm_target_offset(ti, sector); - max_len = ti->max_io_len - sector_div(offset, ti->max_io_len); + if (unlikely(ti->max_io_len & (ti->max_io_len - 1))) + max_len = sector_div(offset, ti->max_io_len); + else + max_len = offset & (ti->max_io_len - 1); + max_len = ti->max_io_len - max_len; if (len > max_len) len = max_len; -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel