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Home -> Community -> Mailing Lists -> Oracle-L -> RE: buffer busy wait & latch free ( cache buffer chain )
Your statement "there are several bugs relating to waiting for latch-free on cache-buffer-chains, and the possibility of the instance hanging. " has me nervous.
I am aware of 1967363 and have obtained the standalone patch for this to be
applied on top of 8.1.7.2 I have
seen significant wait times for cache buffer chains latch in my 8.1.7.1
test environment and am waiting for the
environment to be released to me so that I can upgrade it to
8.1.7.2.1+1967363 (our production is still 8.0.5 !!).
What other bugs are you talking off ?
Hemant
"Binley Lim" <Binley.Lim_at_ird.govt.nz> 05/12/2001 06:10 AM Sent by: root_at_fatcity.com
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
cc: (bcc: CHITALE Hemant Krishnarao/Prin DBA/CSM/ST Group)
Subject: RE: buffer busy wait & latch free ( cache buffer chain )
If on 8.1.7, there are several bugs relating to waiting for latch-free on cache-buffer-chains, and the possibility of the instance hanging.
One is 1967363, and at least two others are still open after applying that patch.
Changing cache buffer latches/buckets is not mentioned in those bugs, and since they are underscored, I would approach with caution.
>>> dcutrone_at_afip.gov.ar 12/05/01 08:30AM >>>
Vivek:
To combat the latch free- cache buffer chain problem, I would first check in v$latch_children if the contention is even across all cache buffer chain latches. If this is the case case (most of the time it is not) , I would add more cache buffer latches. If this is not the case, as ARUN suggested, I would find out which buffers are hot and I would investigate WHY they are hot. (Ussually because of a bad SQL-- you should fix them! )
According to BBW problem, try to identify the segment involved and the cause (p1=file , p2=block and p3=cause from a 10046 trace) and then according to p3 there are some changes that can be done.
HTH
Diego
> What are u seeing the buffer busy waits on is it for the read intensivity
> and latch free is showing that there are hot blocks why dont you find out
> the hot blocks and find what can be done about it
>
>
> >From: "VIVEK_SHARMA" <VIVEK_SHARMA_at_infy.com>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Subject: buffer busy wait & latch free ( cache buffer chain )
> >Date: Tue, 04 Dec 2001 01:55:19 -0800
> >
> >
> >In report.txt we are getting the wait
> >"buffer busy wait" _& wait on "latch free" for "cache buffer chain"
> >
> >Could an excessively Large db_block_buffer cause this ?
> >
> >NOTE - Transaction OLTP in nature
> >
> >NOTE - freelists is set = 2* cpu_count
> >
> >Any oher advice ?
> >
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Binley Lim INET: Binley.Lim_at_ird.govt.nz Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: INET: hemantchitale_at_charteredsemi.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Wed Dec 05 2001 - 01:35:01 CST
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