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snapper: "cpu + waits != DB time" means cpu starvation?

Joaquin GonzalezNov 18 2014 — edited Nov 21 2014

Hi,

Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

I'm using snapper (Tanel Poder's blog: Core IT for Geeks and Pros) to guess what is doing a specific session:

     @snapper all 10 1 7

Sampling SID 7 with interval 10 seconds, taking 1 snapshots...

-- Session Snapper v4.03 BETA - by Tanel Poder ( http://blog.tanelpoder.com ) - Enjoy the Most Advanced Oracle Troubleshooting Script on the Planet!

-------------------------------------------------------------------------------------------------------------------------------------------------------

SID @INST, USERNAME  , TYPE, STATISTIC                                                 ,         DELTA, HDELTA/SEC,    %TIME, GRAPH       , NUM_WAITS,

-------------------------------------------------------------------------------------------------------------------------------------------------------

     7  @1, US_BATCH  , STAT, opened cursors cumulative                                 ,            71,       7,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, recursive calls                                           ,            71,       7,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, recursive cpu usage                                       ,           184,      18,94,         ,             ,          ,

     7  @1, US_BATCH  , STAT, session logical reads                                     ,        246502,     25,37k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, CPU used by this session                                  ,           186,      19,14,         ,             ,          ,

     7  @1, US_BATCH  , STAT, concurrency wait time                                     ,            10,       1,03,         ,             ,          ,

     7  @1, US_BATCH  , STAT, user I/O wait time                                        ,            36,       3,71,         ,             ,          ,

     7  @1, US_BATCH  , STAT, non-idle wait time                                        ,            48,       4,94,         ,             ,          ,

     7  @1, US_BATCH  , STAT, non-idle wait count                                       ,           396,      40,76,         ,             ,          ,

     7  @1, US_BATCH  , STAT, in call idle wait time                                    ,             4,        ,41,         ,             ,          ,

     7  @1, US_BATCH  , STAT, session uga memory                                        ,        320808,     33,02k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, messages sent                                             ,            20,       2,06,         ,             ,          ,

     7  @1, US_BATCH  , STAT, enqueue requests                                          ,            26,       2,68,         ,             ,          ,

     7  @1, US_BATCH  , STAT, enqueue releases                                          ,            27,       2,78,         ,             ,          ,

     7  @1, US_BATCH  , STAT, global enqueue gets sync                                  ,            44,       4,53,         ,             ,          ,

     7  @1, US_BATCH  , STAT, global enqueue releases                                   ,            45,       4,63,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical read total IO requests                           ,             2,        ,21,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical read total bytes                                 ,         32768,      3,37k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical write total IO requests                          ,             4,        ,41,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical write total bytes                                ,         81920,      8,43k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, cell physical IO interconnect bytes                       ,        196608,     20,24k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, gcs messages sent                                         ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, db block gets                                             ,           160,      16,47,         ,             ,          ,

     7  @1, US_BATCH  , STAT, db block gets from cache                                  ,           155,      15,95,         ,             ,          ,

     7  @1, US_BATCH  , STAT, db block gets from cache (fastpath)                       ,            46,       4,73,         ,             ,          ,

     7  @1, US_BATCH  , STAT, db block gets direct                                      ,             5,        ,51,         ,             ,          ,

     7  @1, US_BATCH  , STAT, consistent gets                                           ,        246505,     25,37k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, consistent gets from cache                                ,        246509,     25,37k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, consistent gets from cache (fastpath)                     ,        175274,     18,04k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, consistent gets - examination                             ,         71233,      7,33k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, logical read bytes from cache                             ,    4041572352,    415,98M,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical reads                                            ,             2,        ,21,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical reads cache                                      ,             2,        ,21,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical read IO requests                                 ,             2,        ,21,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical read bytes                                       ,         32768,      3,37k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, db block changes                                          ,           143,      14,72,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical writes                                           ,             5,        ,51,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical writes direct                                    ,             5,        ,51,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical write IO requests                                ,             4,        ,41,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical write bytes                                      ,         81920,      8,43k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical writes non checkpoint                            ,             5,        ,51,         ,             ,          ,

     7  @1, US_BATCH  , STAT, change write time                                         ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, free buffer requested                                     ,             6,        ,62,         ,             ,          ,

     7  @1, US_BATCH  , STAT, commit cleanouts                                          ,            13,       1,34,         ,             ,          ,

     7  @1, US_BATCH  , STAT, commit cleanouts successfully completed                   ,            13,       1,34,         ,             ,          ,

     7  @1, US_BATCH  , STAT, switch current to new buffer                              ,             4,        ,41,         ,             ,          ,

     7  @1, US_BATCH  , STAT, physical writes direct (lob)                              ,             5,        ,51,         ,             ,          ,

     7  @1, US_BATCH  , STAT, shared hash latch upgrades - no wait                      ,             4,        ,41,         ,             ,          ,

     7  @1, US_BATCH  , STAT, calls to kcmgcs                                           ,            20,       2,06,         ,             ,          ,

     7  @1, US_BATCH  , STAT, calls to kcmgas                                           ,            21,       2,16,         ,             ,          ,

     7  @1, US_BATCH  , STAT, calls to get snapshot scn: kcmgss                         ,            99,      10,19,         ,             ,          ,

     7  @1, US_BATCH  , STAT, redo entries                                              ,            96,       9,88,         ,             ,          ,

     7  @1, US_BATCH  , STAT, redo size                                                 ,        141732,     14,59k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, redo size for direct writes                               ,         82100,      8,45k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, redo ordering marks                                       ,             5,        ,51,         ,             ,          ,

     7  @1, US_BATCH  , STAT, redo subscn max counts                                    ,             1,         ,1,         ,             ,          ,

     7  @1, US_BATCH  , STAT, file io wait time                                         ,        260061,     26,77k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, gc local grants                                           ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, gc remote grants                                          ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, undo change vector size                                   ,         24240,      2,49k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, no work - consistent read gets                            ,        176846,      18,2k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, immediate (CURRENT) block cleanout applications           ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, deferred (CURRENT) block cleanout applications            ,             5,        ,51,         ,             ,          ,

     7  @1, US_BATCH  , STAT, commit txn count during cleanout                          ,             1,         ,1,         ,             ,          ,

     7  @1, US_BATCH  , STAT, active txn count during cleanout                          ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, cleanout - number of ktugct calls                         ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, table scans (short tables)                                ,             8,        ,82,         ,             ,          ,

     7  @1, US_BATCH  , STAT, table scan rows gotten                                    ,         54272,      5,59k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, table scan blocks gotten                                  ,           152,      15,64,         ,             ,          ,

     7  @1, US_BATCH  , STAT, table fetch by rowid                                      ,        118879,     12,24k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, table fetch continued row                                 ,          3245,     333,99,         ,             ,          ,

     7  @1, US_BATCH  , STAT, rows fetched via callback                                 ,         58439,      6,01k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, leaf node splits                                          ,             1,         ,1,         ,             ,          ,

     7  @1, US_BATCH  , STAT, leaf node 90-10 splits                                    ,             1,         ,1,         ,             ,          ,

     7  @1, US_BATCH  , STAT, lob writes                                                ,             4,        ,41,         ,             ,          ,

     7  @1, US_BATCH  , STAT, lob writes unaligned                                      ,             4,        ,41,         ,             ,          ,

     7  @1, US_BATCH  , STAT, index fetch by key                                        ,         58450,      6,02k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, index scans kdiixs1                                       ,            14,       1,44,         ,             ,          ,

     7  @1, US_BATCH  , STAT, HSC Heap Segment Block Changes                            ,            22,       2,26,         ,             ,          ,

     7  @1, US_BATCH  , STAT, session cursor cache hits                                 ,            59,       6,07,         ,             ,          ,

     7  @1, US_BATCH  , STAT, buffer is pinned count                                    ,        101399,     10,44k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, buffer is not pinned count                                ,        150506,     15,49k,         ,             ,          ,

     7  @1, US_BATCH  , STAT, workarea memory allocated                                 ,          -465,     -47,86,         ,             ,          ,

     7  @1, US_BATCH  , STAT, workarea executions - optimal                             ,            13,       1,34,         ,             ,          ,

     7  @1, US_BATCH  , STAT, execute count                                             ,            59,       6,07,         ,             ,          ,

     7  @1, US_BATCH  , STAT, bytes sent via SQL*Net to dblink                          ,           980,     100,87,         ,             ,          ,

     7  @1, US_BATCH  , STAT, bytes received via SQL*Net from dblink                    ,            12,       1,24,         ,             ,          ,

     7  @1, US_BATCH  , STAT, SQL*Net roundtrips to/from dblink                         ,             3,        ,31,         ,             ,          ,

     7  @1, US_BATCH  , STAT, sorts (memory)                                            ,             6,        ,62,         ,             ,          ,

     7  @1, US_BATCH  , STAT, sorts (rows)                                              ,            92,       9,47,         ,             ,          ,

     7  @1, US_BATCH  , TIME, repeated bind elapsed time                                ,            44,     4,53us,      .0%, [          ],          ,

     7  @1, US_BATCH  , TIME, PL/SQL execution elapsed time                             ,        151993,    15,64ms,     1.6%, [#         ],          ,

     7  @1, US_BATCH  , TIME, DB CPU                                                    ,       2386412,   245,62ms,    24.6%, [@@@       ],          ,

     7  @1, US_BATCH  , TIME, sql execute elapsed time                                  ,      10065556,      1,04s,   103.6%, [##########],          ,

     7  @1, US_BATCH  , TIME, DB time                                                   ,      10065556,      1,04s,   103.6%, [##########],          ,

     7  @1, US_BATCH  , TIME, sequence load elapsed time                                ,          7580,   780,18us,      .1%, [          ],          ,

     7  @1, US_BATCH  , WAIT, latch: cache buffers chains                               ,           261,    26,86us,      .0%, [          ],         1,

     7  @1, US_BATCH  , WAIT, db file sequential read                                   ,        260061,    26,77ms,     2.7%, [W         ],         2,

     7  @1, US_BATCH  , WAIT, gc cr grant 2-way                                         ,           515,    53,01us,      .0%, [          ],         1,

     7  @1, US_BATCH  , WAIT, gc current grant 2-way                                    ,           256,    26,35us,      .0%, [          ],         1,

     7  @1, US_BATCH  , WAIT, gc current grant busy                                     ,           292,    30,05us,      .0%, [          ],         1,

     7  @1, US_BATCH  , WAIT, direct path write                                         ,          4624,   475,93us,      .0%, [          ],         3,

     7  @1, US_BATCH  , WAIT, row cache lock                                            ,          1035,   106,53us,      .0%, [          ],        12,

     7  @1, US_BATCH  , WAIT, latch: shared pool                                        ,         95594,     9,84ms,     1.0%, [W         ],         3,

     7  @1, US_BATCH  , WAIT, BFILE read                                                ,           117,    12,04us,      .0%, [          ],         5,

     7  @1, US_BATCH  , WAIT, utl_file I/O                                              ,         92538,     9,52ms,     1.0%, [W         ],       346,

     7  @1, US_BATCH  , WAIT, External Procedure call                                   ,           331,    34,07us,      .0%, [          ],         4,

     7  @1, US_BATCH  , WAIT, HS message to agent                                       ,         55683,     5,73ms,      .6%, [W         ],         8,

     7  @1, US_BATCH  , WAIT, events in waitclass Other                                 ,          8513,    876,2us,      .1%, [          ],        20,

--  End of Stats snap 1, end=2014-11-18 16:58:49, seconds=9,7

----------------------------------------------------------------------------------------------------

Active% | INST | SQL_ID          | SQL_CHILD | EVENT                               | WAIT_CLASS

----------------------------------------------------------------------------------------------------

    92% |    1 | ghxd2trbvvubg   | 0         | ON CPU                              | ON CPU

     2% |    1 | 67w54h1j9gj0q   | 1         | db file sequential read             | User I/O

     2% |    1 | 67w54h1j9gj0q   | 1         | ON CPU                              | ON CPU

     2% |    1 | gtnwbkt3bastt   | 0         | utl_file I/O                        | User I/O

     1% |    1 |                 |           | latch: shared pool                  | Concurrency

--  End of ASH snap 1, end=2014-11-18 16:58:49, seconds=10, samples_taken=93

Normaly DB time ~= total waits + db cpu, isn't it?

As you can see that's not the case shown. What could it mean? cpu starvation? process swapping?

Any clue?

Thanks.

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