[LU-5548] avoid list scan in ptlrpcd_check

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.7.0, Lustre 2.5.4
• Severity: 3
• Assignee: Liang Zhen (Inactive)
• Reporter: Liang Zhen (Inactive)

Description

ptlrpcd_check() always scan all requests on ptlrpc_request_set::set_requests and try to finish completed requests, this is low efficiency. Even worse, l_wait_event() always checks condition for twice before sleeping and one more time after waking up, which means it will call ptlrpcd_check() for three times in each loop.

The solution is quite simple, ptlrpc_check_set() can move completed requests at head of ptlrpc_request_set::set_requests, so ptlrpcd_check doesn't need to scan all requests on a rqset anymore.

This is an improvement for LU-5053.