[LU-9885] Huge amount of costs in ptlrpc_wait_event() at file creation

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Affects Version/s: Lustre 2.7.0
• Severity: 3
• Assignee: Peter Jones
• Reporter: Shuichi Ihara (Inactive)

Description

After metadata performance improvements on LU-9796, we are hitting Lustre level bottleneck at File creation for scale.
collected cost of all Lustre functions at file creation, ptlrpc_wait_event() took huge a mount of time cost.

[root@mds05 ~]# /work/ihara/perf-tools/bin/funccost -L
Start setting lustre functions...
Setting lustre functions done...
Tracing "[lustre modules functions]"... Ctrl-C to end.
/work/ihara/perf-tools/bin/funccost: line 158: tracing_enabled: Permission denied
^C
FUNC                           TOTAL_TIME(us)       COUNT        AVG(us)       
ptlrpc_wait_event              1299908760           1745217      744.84      
ptlrpc_server_handle_request   279979924            876419       319.46      
tgt_request_handle             268911684            637004       422.15      
tgt_enqueue                    230880245            318456       725.00      
ldlm_lock_enqueue              230872744            1273842      181.24      
ldlm_handle_enqueue0           230791830            318456       724.72      
mdt_intent_policy              224904050            318456       706.23      
mdt_intent_opc                 223658324            318456       702.32      
mdt_intent_reint               223196495            318456       700.87      

Why is ptlrpc_wait_event() taking a ot costs here?

Issue Links

• is related to: LU-14976 Changing tbf policy induces high CPU load