This is a note to let you know that I've just added the patch titled
RDMA/hns: Optimize hem allocation performance
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rdma-hns-optimize-hem-allocation-performance.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 46a35a1180e2f385923bcb66cd5fc78fd85d6406
Author: Junxian Huang <huangjunxian6@xxxxxxxxxxxxx>
Date: Fri Sep 6 17:34:43 2024 +0800
RDMA/hns: Optimize hem allocation performance
[ Upstream commit fe51f6254d81f5a69c31df16353d6539b2b51630 ]
When allocating MTT hem, for each hop level of each hem that is being
allocated, the driver iterates the hem list to find out whether the
bt page has been allocated in this hop level. If not, allocate a new
one and splice it to the list. The time complexity is O(n^2) in worst
cases.
Currently the allocation for-loop uses 'unit' as the step size. This
actually has taken into account the reuse of last-hop-level MTT bt
pages by multiple buffer pages. Thus pages of last hop level will
never have been allocated, so there is no need to iterate the hem list
in last hop level.
Removing this unnecessary iteration can reduce the time complexity to
O(n).
Fixes: 38389eaa4db1 ("RDMA/hns: Add mtr support for mixed multihop addressing")
Signed-off-by: Junxian Huang <huangjunxian6@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20240906093444.3571619-9-huangjunxian6@xxxxxxxxxxxxx
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/infiniband/hw/hns/hns_roce_hem.c b/drivers/infiniband/hw/hns/hns_roce_hem.c
index 5f2b434541a2d..ce2ace2c850dc 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hem.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hem.c
@@ -1182,10 +1182,12 @@ static int hem_list_alloc_mid_bt(struct hns_roce_dev *hr_dev,
/* config L1 bt to last bt and link them to corresponding parent */
for (level = 1; level < hopnum; level++) {
- cur = hem_list_search_item(&mid_bt[level], offset);
- if (cur) {
- hem_ptrs[level] = cur;
- continue;
+ if (!hem_list_is_bottom_bt(hopnum, level)) {
+ cur = hem_list_search_item(&mid_bt[level], offset);
+ if (cur) {
+ hem_ptrs[level] = cur;
+ continue;
+ }
}
step = hem_list_calc_ba_range(hopnum, level, unit);
