Re: performance modality in 7.1 for large text attributes?

From: Christopher Masto <chris(at)netmonger(dot)net>
To: Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu>, Paul A Vixie <vixie(at)mfnx(dot)net>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: performance modality in 7.1 for large text attributes?
Date: 2000-12-19 18:01:56
Message-ID: 20001219130156.A1138@netmonger.net
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On Tue, Dec 19, 2000 at 03:03:43PM +0000, Thomas Lockhart wrote:
> o WAL fsync() log commits and cleanup (aggregate throughput is great,
> but every once in a while someone waits while the paperwork gets done.
> Waiting may be due to processor resource competition)
>
> o Underlying file system bookkeeping from the kernel. e.g. flushing
> buffers to disk etc etc.

I was going to suggest the same, but it's interesting that it happens
on reads as well. I can't tell for sure from the graph, but it looks
like it happens fairly consistently - every Nth time. I'd be curious
to see how this changes if you artificially slow down your loop, or
adjust your OS's filesystem parameters. It may give some more clues.
--
Christopher Masto Senior Network Monkey NetMonger Communications
chris(at)netmonger(dot)net info(at)netmonger(dot)net http://www.netmonger.net

Free yourself, free your machine, free the daemon -- http://www.freebsd.org/

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