Hi Sergey, sorry for the late response, missed this
patch.
On 03/13/2018 05:25 PM, Sergey Gorenko wrote:
Some users complain about RNR errors on the target, when heavy
high-priority tasks run on the initiator. After the
investigation, we found out that the receive WRs were exhausted,
because the initiator could not post them on time.
Receive work reqeusts are posted in chunks of min_posted_rx to
reduce the number of hits to the HCA. The WRs are posted in the
receive completion handler when the number of free receive buffers
reaches min_posted_rx. But on a high-loaded host, receive CQEs
processing can be delayed and all receive WRs will be exhausted.
In this case, the target will get an RNR error.
To avoid this, we post receive WR, as soon as at least one receive
buffer is freed. This increases the number of hits to the HCA, but
test results show that performance degradation is not significant.
Overall this looks fine, small comments below.
@@ -322,30 +319,28 @@ void iser_free_rx_descriptors(struct iser_conn *iser_conn)
static int iser_post_rx_bufs(struct iscsi_conn *conn, struct iscsi_hdr *req)
{
struct iser_conn *iser_conn = conn->dd_data;
- struct ib_conn *ib_conn = &iser_conn->ib_conn;
struct iscsi_session *session = conn->session;
+ /* There is one posted recv buffer (for the last login response). */
+ int already_posted = 1;
No need for a local variable for a constant really.
+ int i;
iser_dbg("req op %x flags %x\n", req->opcode, req->flags);
/* check if this is the last login - going to full feature phase */
if ((req->flags & ISCSI_FULL_FEATURE_PHASE) != ISCSI_FULL_FEATURE_PHASE)
return 0;
- /*
- * Check that there is one posted recv buffer
- * (for the last login response).
- */
- WARN_ON(ib_conn->post_recv_buf_count != 1);
-
if (session->discovery_sess) {
iser_info("Discovery session, re-using login RX buffer\n");
return 0;
} else
iser_info("Normal session, posting batch of RX %d buffers\n",
- iser_conn->min_posted_rx);
+ iser_conn->qp_max_recv_dtos - already_posted);
/* Initial post receive buffers */
- if (iser_post_recvm(iser_conn, iser_conn->min_posted_rx))
- return -ENOMEM;
+ for (i = already_posted; i < iser_conn->qp_max_recv_dtos; i++) {
+ if (iser_post_recvm(iser_conn, &iser_conn->rx_descs[i]))
+ return -ENOMEM;
+ }
Please propagate the return code here.
--
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