Re: What does "koh-kghu call " mean?

Jonathan Lewis wrote:
>
> "Connor McDonald" <connor_mcdonald_at_yahoo.com> wrote in message
> news:442681C3.6D75_at_yahoo.com...
> > Jonathan Lewis wrote:
> >>
> >> In the SGA management, there are 255 lists, of which the
> >> first 200 or so are each for a very specific chunk size
> >> (changine by four bytes as you go from list to list) then
> >> about 50 with size ranges. This lets Oracle find free memory
> >> very rapidly for SGA management - possibly the same code
> >> has been applied for the PGA with fewer items in the list,
> >> therefore a greater need to standard the use of chunk sizes
> >> and minimize the possible chunk count. One strategy for
> >> this would be to 'predict' the need for large chunks than
> >> the actual code call demanded. If you change my test from
> >> 4K strings to 16K strings, I think the allocation jumped to
> >> chunks of 64K.
> >>
>
> >
> > Can't remember where I read it, and certainly haven't tried to verify
> > it, but from 10.2, the 255 lists apparently have been raised to 4096.
> >
>
> Just did a quick check.
>
> It hasn't changed from 255, but the free memory
> for the reserved pool has been split from a single
> free list to a set of 14 free lists with the following
> lower limits:
>
> Reserved bucket 0 size=16
> Reserved bucket 1 size=4400
> Reserved bucket 2 size=8204
> Reserved bucket 3 size=8460
> Reserved bucket 4 size=8464
> Reserved bucket 5 size=8468
> Reserved bucket 6 size=8472
> Reserved bucket 7 size=9296
> Reserved bucket 8 size=9300
> Reserved bucket 9 size=12320
> Reserved bucket 10 size=12324
> Reserved bucket 11 size=16396
> Reserved bucket 12 size=32780
> Reserved bucket 13 size=65548
>
> I believe there was a paper at Oracle World this
> year that said that they were trying to increase the
> use of standard size chunks of 1K and 4K in the shared
> pool. Perhaps that's where your memory of 4096 cam
> from.
>
> --
> Regards
>
> Jonathan Lewis
> http://www.oracle.com/technology/community/oracle_ace/ace1.html#lewis
>
> The Co-operative Oracle Users' FAQ
> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>
> Cost Based Oracle: Fundamentals
> http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

ah, thats jogged the memory. I was scanning through the slides from JB's OOW presentation and read "4096 chunk sizes" from the slides. A more careful check through the accompanying white paper gave a better clarification.

Cheers
Connor

-- 
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
Co-author: "Oracle Insight - Tales of the OakTable"

web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald_at_yahoo.com


"Semper in excremento, sole profundum qui variat."

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