[LU-1248] all mdt_rdpg_* threads busy in osd_ea_fid_get()

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Affects Version/s: Lustre 2.1.0
• Environment: https://github.com/chaos/lustre/tree/2.1.0-llnl
• Severity: 3
• Assignee: Lai Siyao
• Reporter: Ned Bass (Inactive)

Description

The load average on the MDS for a classified production 2.1 filesystem jumped to over 400. Top showed mdt_rdpg_* threads all using 4-7% CPU time. This may have been due to a pathological workload, but we were wondering if there's something like an overly contended lock in ldiskfs going on here.

Most of the stacks looked like this:

__cond_resched
_cond_resched
ifind_fast
iget_locked
ldiskfs_iget
? generic_detach_inode
osd_iget
osd_ea_fid_get
osd_it_ea_rec
mdd_readpage
cml_readpage
mdt_readpage
? mdt_unpack_req_pack_rep
mdt_handle_common
? lustre_msg_get_transno
mdt_readpage_handle
ptlrpc_main
child_rip