Re: [HACKERS] 8.3beta1 testing on Solaris

From: "Jignesh K(dot) Shah" <J(dot)K(dot)Shah(at)Sun(dot)COM>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org, Gregory Stark <stark(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [HACKERS] 8.3beta1 testing on Solaris
Date: 2007-10-26 13:36:53
Message-ID: 4721ED75.7090607@sun.com
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I agree with Tom.. somehow I think increasing NUM_CLOG_BUFFERS is just
avoiding the symptom to a later value.. I promise to look more into it
before making any recommendations to increase NUM_CLOG_BUFFERs.

Because though "iGen" showed improvements in that area by increasing
num_clog_buffers , EAStress had shown no improvements.. Plus the reason
I think this is not the problem in 8.3beta1 since the Lock Output
clearly does not show CLOGControlFile as to be the issue which I had
seen in earlier case. So I dont think that increasing NUM_CLOG_BUFFERS
will change thing here.

Now I dont understand the code pretty well yet I see three hotspots and
not sure if they are related to each other
* ProcArrayLock waits - causing Waits as reported by
83_lockwait.d script
* SimpleLRUReadPage - causing read IOs as reported by
iostat/rsnoop.d
* GetSnapshotData - causing CPU utilization as reported by hotuser

But I will shut up and do more testing.

Regards,
Jignesh

Tom Lane wrote:
> Josh Berkus <josh(at)agliodbs(dot)com> writes:
>
>> Actually, 32 made a significant difference as I recall ... do you still have
>> the figures for that, Jignesh?
>>
>
> I'd want to see a new set of test runs backing up any call for a change
> in NUM_CLOG_BUFFERS --- we've changed enough stuff around this area that
> benchmarks using code from a few months back shouldn't carry a lot of
> weight.
>
> regards, tom lane
>

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