RE: linux kernel parameters

From: Clay Jackson (cjackson) <"Clay>
Date: Sun, 14 Feb 2021 00:15:02 +0000
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OK - I feel compelled to jump in here - I'm nowhere near the DBA Mladen is; but, to paraphrase, I know a thing or two about Linux because I've seen a thing or two, INCLUDING what happens if SMMNS is less than SEMMSL*SEMMNI.

Bottom line (at least in Fedora and RHEL 5, which is where I saw this - I'll admit I haven't "tested" it since"; but, once bitten, twice shy) SEMMNS wins, always.

See also https://access.redhat.com/solutions/1437013

If SEMMSL*SEMMNI is less than SEMMNS, you'll only get SMMNS semaphores, NOT SMMSL_at_SEMMNI. Linux is quite "forgiving" that way, if you really want to shoot yourself in the foot, it won't stop you.

And trusting w/o verifying what ANY support person tells you is a fool's errand.

Clay Jackson

-----Original Message-----
From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> On Behalf Of dimensional.dba_at_comcast.net Sent: Saturday, February 13, 2021 1:30 PM To: gogala.mladen_at_gmail.com; oracle-l_at_freelists.org Subject: RE: linux kernel parameters

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You are very funny Mladen. I have never said in any post here, that I don't like you. I just believe in facts.
The facts do not support your argument and the RedHat/Oracle documentation doesn't either. The Oracle values that Oracle itself sets on Exadata, a fully run and managed Oracle device, doesn't support your argument.

Oracle Support has given a recommendation rather you like it or not. The originally poster can decide to use those values or not to try and resolve their issue. There is nothing wrong with those values as Linux will accept them (will not damage the system), then follow the rules embedded in the source code as to what it determines or needs for the resource requirements on the system.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> On Behalf Of Mladen Gogala Sent: Saturday, February 13, 2021 1:11 PM To: dimensional.dba_at_comcast.net; oracle-l_at_freelists.org Subject: Re: linux kernel parameters

Which ones? I have explained the semantics of the semaphore parameters. Nobody questioned that semantics. The rest of my statements logically follows that syntax. The statement that SEMMNS should be larger or equal, idally equal, to SEMMSL*SEMMNI follows from that syntax. If SEMMNS < SEMMSL*SEMMNI then you will not be able to allosace SEMMNI semaphore sets with the length of SEMMSL. That is the reason for my objection to 3000 32000 3000 128 advice. That advice was obviously given by a junior support analyst who doesn't understand semaphores very well because that recommendation doesn't conform to the semantics of the semaphore parameters.

This feels like whipping a dead horse. We're getting nowhere. I understand that you don't like me, but the facts are the facts.

On 2/13/21 3:13 PM, dimensional.dba_at_comcast.net wrote:
> It is not about being right, it is about being technically accurate.
> You make statements with no facts.

--
Mladen Gogala
Database Consultant
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Received on Sun Feb 14 2021 - 01:15:02 CET

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