Cache buffer chains (kslbegin)
- From: "Stephen Anderson" <st.anderson@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Mon, 24 Apr 2006 14:39:23 +0100
Hello,
I have a 10 minute statspack report from a busy time period, and have seen
that buffer busy waits were the highest wait events. Would I be correct to
then look at the Latch Miss Source at the largest sleeps? I have the
following information there:
Latch Sleep breakdown for DB: MERLIN Instance: MERLIN Snaps: 244 -245
-> ordered by misses desc
Get Spin &
Latch Name Requests Misses Sleeps Sleeps
1->4
-------------------------- -------------- ----------- -----------
------------
cache buffers chains 156,103,492 15,773 4,067 0/0/0/0/0
simulator hash latch 5,788,739 604 25
579/25/0/0/0
multiblock read objects 502,619 472 51
421/51/0/0/0
library cache 486,962 409 44
365/44/0/0/0
-------------------------------------------------------------
Latch Miss Sources for DB: MERLIN Instance: MERLIN Snaps: 244 -245
-> only latches with sleeps are shown
-> ordered by name, sleeps desc
NoWait
Waiter
Latch Name Where Misses Sleeps
Sleeps
------------------------ -------------------------- ------- ----------
--------
cache buffers chains kcbgtcr: kslbegin excl 0 2,439
3,749
cache buffers chains kcbrls: kslbegin 0 973
58
cache buffers chains kcbzib: multi-block read: 0
308 0
cache buffers chains kcbzgb: scan from tail. no 0
199 0
....
Can anyone confirm what "kslbegin excl" is? I found something listing
kslbegin as a "macro to lock a latch", but didn't realise you could lock a
latch in anything other than exclusive. With high sleeps on "kslbegin
excl", where would be the best place to start digging into what caused these
cache buffer chain sleeps?
Many thanks,
Steve.
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