Re: Libpq is very slow on windows but fast on linux.

From: Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>
To: Rob Brown-Bayliss <r(dot)brown(dot)bayliss(at)gmail(dot)com>
Cc: John R Pierce <pierce(at)hogranch(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: Libpq is very slow on windows but fast on linux.
Date: 2010-11-08 02:19:26
Message-ID: 4CD75E2E.60405@postnewspapers.com.au
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On 07/11/10 09:13, Rob Brown-Bayliss wrote:
> Ok, So I did that, in the windows capture file are many many lines of
> Red text on a black background, I assume thats a bad thing.

If you examine the packet it'll say "invalid checksum". This will be
because your network card is doing TCP checksum offloading, and you can
almost certainly ignore the warning or turn it off. See:

http://wiki.wireshark.org/TCP_Checksum_Verification
http://www.wireshark.org/docs/wsug_html_chunked/ChAdvChecksums.html

> As I said before I really don't know what I am looking at.

Use the wireshark throughput graph for a starter. If you don't
understand TCP/IP, wireshark probably won't help you much - but then, I
learned about TCP/IP with wireshark. Consider doing the same - dive in,
read about it, and have a play.

I won't be too surprised if the issue turns out to be related to TCP
window sizes and window scaling differences between the two machines.

--
Craig Ringer

Tech-related writing: http://soapyfrogs.blogspot.com/

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