[LU-5557] enqueue and reint RPC are not tracked in MDS stats

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.7.0
• Affects Version/s: Lustre 2.6.0, Lustre 2.5.2, Lustre 2.4.3
• Labels: llnl
• Assignee: John Hammond
• Reporter: Aurelien Degremont (Inactive)

Description

MDS stats proc file /proc/fs/lustre/mds/MDS/mdt/stats does not track information about LDLM_ENQUEUE and MDS_REINT RPCs.
This class of RPC covers most of "modifying" RPCs on MDS. This file displays mostly RPC that "read" data from MDT device and which is not "writing" on the device.

$ cat /proc/fs/lustre/mds/MDS/mdt/stats
snapshot_time             1409239309.161365 secs.usecs
req_waittime              182 samples [usec] 17 420 19191 2604647
req_qdepth                182 samples [reqs] 0 1 3 3
req_active                182 samples [reqs] 1 3 251 403
req_timeout               182 samples [sec] 1 10 209 479
reqbuf_avail              463 samples [bufs] 64 64 29632 1896448
ldlm_ibits_enqueue        5 samples [reqs] 1 1 5 5
mds_getattr               1 samples [usec] 83 83 83 6889
mds_connect               6 samples [usec] 20 197 439 54031
mds_getstatus             1 samples [usec] 76 76 76 5776
mds_statfs                2 samples [usec] 74 95 169 14501
obd_ping                  167 samples [usec] 12 130 5875 249977

These class of RPCs are explicitly blacklisted in the code for a very long time.

+++ b/lustre/ptlrpc/service.c
@@ -2110,7 +2110,7 @@ put_conn:
         if (likely(svc->srv_stats != NULL && request->rq_reqmsg != NULL)) {
                 __u32 op = lustre_msg_get_opc(request->rq_reqmsg);
                 int opc = opcode_offset(op);
                 if (opc > 0 && !(op == LDLM_ENQUEUE || op == MDS_REINT)) {
                         LASSERT(opc < LUSTRE_MAX_OPCODES);
                         lprocfs_counter_add(svc->srv_stats,
                                             opc + EXTRA_MAX_OPCODES,

Is there some specific reasons to prevent that?

Could we consider enabling them?