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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!

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

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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

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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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Added on Nov 18 2014

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