3.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vu Pham <vu@xxxxxxxxxxxx>
commit f01b9f73392b48c6cda7c2c66594c73137c776da upstream.
This patch changes isert_reg_rdma_frwr() to not use FRMR for single
dma entry requests from small I/Os, in order to avoid the associated
memory registration overhead.
Using DMA MR is sufficient here for the single dma entry requests,
and addresses a >= v3.12 performance regression.
Signed-off-by: Vu Pham <vu@xxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/infiniband/ulp/isert/ib_isert.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -2259,18 +2259,26 @@ isert_reg_rdma_frwr(struct iscsi_conn *c
data_len = min(data_left, rdma_write_max);
wr->cur_rdma_length = data_len;
- spin_lock_irqsave(&isert_conn->conn_lock, flags);
- fr_desc = list_first_entry(&isert_conn->conn_frwr_pool,
- struct fast_reg_descriptor, list);
- list_del(&fr_desc->list);
- spin_unlock_irqrestore(&isert_conn->conn_lock, flags);
- wr->fr_desc = fr_desc;
+ /* if there is a single dma entry, dma mr is sufficient */
+ if (count == 1) {
+ ib_sge->addr = ib_sg_dma_address(ib_dev, &sg_start[0]);
+ ib_sge->length = ib_sg_dma_len(ib_dev, &sg_start[0]);
+ ib_sge->lkey = isert_conn->conn_mr->lkey;
+ wr->fr_desc = NULL;
+ } else {
+ spin_lock_irqsave(&isert_conn->conn_lock, flags);
+ fr_desc = list_first_entry(&isert_conn->conn_frwr_pool,
+ struct fast_reg_descriptor, list);
+ list_del(&fr_desc->list);
+ spin_unlock_irqrestore(&isert_conn->conn_lock, flags);
+ wr->fr_desc = fr_desc;
- ret = isert_fast_reg_mr(fr_desc, isert_cmd, isert_conn,
- ib_sge, offset, data_len);
- if (ret) {
- list_add_tail(&fr_desc->list, &isert_conn->conn_frwr_pool);
- goto unmap_sg;
+ ret = isert_fast_reg_mr(fr_desc, isert_cmd, isert_conn,
+ ib_sge, offset, data_len);
+ if (ret) {
+ list_add_tail(&fr_desc->list, &isert_conn->conn_frwr_pool);
+ goto unmap_sg;
+ }
}
return 0;
--
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