"cache buffer chains" misses > 0 and spins & sleep[1-4] are zero, yet sleeps > 0
- From: Christo Kutrovsky <kutrovsky.oracle@xxxxxxxxx>
- To: oracle-l <oracle-l@xxxxxxxxxxxxx>
- Date: Sat, 4 Jun 2005 14:01:00 -0400
Hello all,
Latch Sleep breakdown for DB: WEBP1 Instance: webp1 Snaps: 32412 -32413
-> ordered by misses desc
Get Spin &
Latch Name Requests Misses Sleeps Sleeps 1-=
>4
-------------------------- -------------- ----------- ----------- ---------=
---
...
cache buffers chains 30,194,375 1,980 133 0/0/0/0/0
...
I am looking at this statspack extract over 20 minutes. I have a very
specific question.
Given that I have ~2000 misses and 133 sleeps, howcome I dont have
anything in spins and sleeps[1-4] ?
Are the cache buffer chains special, i.e. there is no spinning to
acquire them ? And if there are sleeps, last column is supposed to be
4 or more, yet it is still zero?
Looking in v$latch:
ADDR=095000D3E0
LATCH#=0998
LEVEL#=091
NAME=09cache buffers chains
GETS=09113996341015
MISSES=09286248205
SLEEPS=092787346
IMMEDIATE_GETS=093233325716
IMMEDIATE_MISSES=0912384650
WAITERS_WOKEN=090
WAITS_HOLDING_LATCH=092933754
SPIN_GETS=090
SLEEP1=090
SLEEP2=090
SLEEP3=090
SLEEP4=090
SLEEP5=090
SLEEP6=090
SLEEP7=090
SLEEP8=090
SLEEP9=090
SLEEP10=090
SLEEP11=090
WAIT_TIME=090
You can see there's a large number of gets/misses but NONE in
spin_gets and sleeps 1-4, why is that ?
--=20
Christo Kutrovsky
Database/System Administrator
The Pythian Group
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