RE: ASMM
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <orahawk@xxxxxxxxx>, <Brian.Zelli@xxxxxxxxxxxxxxx>
- Date: Fri, 16 May 2014 16:50:08 -0400
That is a possibility. Looking at your resize operations will tell you what is
going on.
Two bad cases are possible: 1) lots of literals and/or unique queries so the
shared pool wants to grow and AMM pushes the boundary; 2) Hourly grow shrink
near the stable point swapping only a few granules between shared pool and
buffer cache, so both recent buffer reads and recent parses tend to get
discarded.
Both are good reasons to turn AMM off, especially if you know about what a good
size range is for the overall SGA.
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Dragutin Jastrebic
Sent: Friday, May 16, 2014 3:59 PM
To: Brian.Zelli@xxxxxxxxxxxxxxx
Cc: oracle-l (oracle-l@xxxxxxxxxxxxx)
Subject: Re: ASMM
=>
I am finding that my Library Cache Get hit Ratio % is hovering around 50-60
percent. I am running AMM and I set
the memory_target twice what it was and still no relief…..
Brian
<=
Hello
I remember that I have faced a strange behaviour with 10g and SGA_target on one
or even two projects.
Oracle was constantly resizing the shared_pool and the buffer_cache and this
shrink-grow activity between the two was
constantly eliminating some queries from the shared_pool, lowering the library
cache hit ratio.
The view that shows this shrink-grow behaviour inside the SGA is
v$sga_resize_ops.
It was couple of years ago so hopefully this behaviour is improved with new
patches/versions of Oracle, however
maybe you can still check this.
HTH
Dragutin
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