Ceph

when i use fio to test rbd performance (4kb random write) , i found that osd::op_w_latency which i got from perf counter is much larger than the latency reported by fio, after i digged into it and found that, with XFS , after data is written to journal , osd sends a reply to client to imply that the write request has completed , it updates the osd::op_w_latency perf counter in ReplicatedPG::eval_repop function , when data is written to filestore, the osd::op_w_latency perf counter updates again, so op_w_latency perf counter records the apply latency , not the commit latency , is this the defined behavior or a bug?