@@ -157,15 +157,17 @@ void rpc_count_iostats_metrics(const struct rpc_task *task,
spin_lock(&op_metrics->om_lock);
op_metrics->om_ops++;
- op_metrics->om_ntrans += req->rq_ntrans;
+ /* kernel API: om_ops must never become larger than om_ntrans */
+ op_metrics->om_ntrans += max(req->rq_ntrans, 1);
op_metrics->om_timeouts += task->tk_timeouts;
op_metrics->om_bytes_sent += req->rq_xmit_bytes_sent;
op_metrics->om_bytes_recv += req->rq_reply_bytes_recvd;
- delta = ktime_sub(req->rq_xtime, task->tk_start);
- op_metrics->om_queue = ktime_add(op_metrics->om_queue, delta);
-
+ if (ktime_to_ns(req->rq_xtime)) {
+ delta = ktime_sub(req->rq_xtime, task->tk_start);
+ op_metrics->om_queue = ktime_add(op_metrics->om_queue, delta);
+ }
op_metrics->om_rtt = ktime_add(op_metrics->om_rtt, req->rq_rtt);
delta = ktime_sub(now, task->tk_start);
I noticed recently that during an xfstests on a krb5i mount, the retransmit count for certain operations had gone negative, and the backlog value became unreasonably large. I recall that Andy has pointed this out to me in the past. When call_refresh fails to find a valid credential for an RPC, the RPC exits immediately without sending anything on the wire. This leaves rq_ntrans, rq_xtime, and rq_rtt set to zero. The solution for om_queue is to not add the to RPC's running backlog queue total whenever rq_xtime is zero. For om_ntrans, it's a bit more difficult. A zero rq_ntrans causes om_ops to become larger than om_ntrans. The design of the RPC metrics API assumes that ntrans will always be equal to or larger than the ops count. The result is that when an RPC fails to find credentials, the RPC operation's reported retransmit count, which is computed in user space as the difference between ops and ntrans, goes negative. Ideally the kernel API should report a separate retransmit and "exited before initial transmission" metric, so that user space can sort out the difference properly. To avoid kernel API changes and changes to the way rq_ntrans is used when performing transport locking, account for untransmitted RPCs so that om_ntrans keeps up with om_ops: always add one or more to om_ntrans. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> --- net/sunrpc/stats.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html