hi, everyone

when I user rest bench testing RGW with cmd : rest-bench --access-key=ak 
--secret=sk  --bucket=bucket --seconds=360 -t 200  -b 524288  --no-cleanup 
write 

I found when RGW call the method "bucket_prepare_op " is very slow. so I 
observed from 'dump_historic_ops',to see:
{ "description": "osd_op(client.4211.0:265984 .dir.default.4148.1 [call 
rgw.bucket_prepare_op] 3.b168f3d0 e37)",
          "received_at": "2014-07-03 11:07:02.465700",
          "age": "308.315230",
          "duration": "3.401743",
          "type_data": [
                "commit sent; apply or cleanup",
                { "client": "client.4211",
                  "tid": 265984},
                [
                    { "time": "2014-07-03 11:07:02.465852",
                      "event": "waiting_for_osdmap"},
                    { "time": "2014-07-03 11:07:02.465875",
                      "event": "queue op_wq"},
                    { "time": "2014-07-03 11:07:03.729087",
                      "event": "reached_pg"},
                    { "time": "2014-07-03 11:07:03.729120",
                      "event": "started"},
                    { "time": "2014-07-03 11:07:03.729126",
                      "event": "started"},
                    { "time": "2014-07-03 11:07:03.804366",
                      "event": "waiting for subops from [19,9]"},
                    { "time": "2014-07-03 11:07:03.804431",
                      "event": "commit_queued_for_journal_write"},
                    { "time": "2014-07-03 11:07:03.804509",
                      "event": "write_thread_in_journal_buffer"},
                    { "time": "2014-07-03 11:07:03.934419",
                      "event": "journaled_completion_queued"},
                    { "time": "2014-07-03 11:07:05.297282",
                      "event": "sub_op_commit_rec"},
                    { "time": "2014-07-03 11:07:05.297319",
                      "event": "sub_op_commit_rec"},
                    { "time": "2014-07-03 11:07:05.311217",
                      "event": "op_applied"},
                    { "time": "2014-07-03 11:07:05.867384",
                      "event": "op_commit finish lock"},
                    { "time": "2014-07-03 11:07:05.867385",
                      "event": "op_commit"},
                    { "time": "2014-07-03 11:07:05.867424",
                      "event": "commit_sent"},
                    { "time": "2014-07-03 11:07:05.867428",
                      "event": "op_commit finish"},
                    { "time": "2014-07-03 11:07:05.867443",
                      "event": "done"}]]}]}

so I find 2 performance degradation. one is from "queue op_wq" to "reached_pg" 
, anothor is from "journaled_completion_queued" to "op_commit".
and I must stess that there are so many ops write to one bucket object, so how 
to reduce Latency ?





baijia...@126.com
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