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Re: SO_SNDBUF size is small on win32?

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Martijn van Oosterhout <kleptog(at)svana(dot)org>
Cc: Yoshiyuki Asaba <y-asaba(at)sraoss(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: SO_SNDBUF size is small on win32?
Date: 2006-06-27 15:45:53
Message-ID: 44A152B1.1020302@dunslane.net (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Martijn van Oosterhout wrote:

>On Wed, Jun 28, 2006 at 12:23:13AM +0900, Yoshiyuki Asaba wrote:
>  
>
>>Hi,
>>
>>I see a performance issue on win32. This problem is causes by the
>>following URL. 
>>
>>http://support.microsoft.com/kb/823764/EN-US/
>>
>>On win32, default SO_SNDBUF value is 8192 bytes. And libpq's buffer is
>>8192 too.
>>    
>>
>
>Ok, so there's a difficiency in Windows TCP code. Do you have any
>benchmarks to show this actually makes a difference. According to the
>URL you give, the problem occurs if the libpq buffer is *bigger* than
>the socket buffer, which it isn't...
>  
>

No, it says it occurs if this condition is met: "A single *send* call or 
*WSASend* call fills the whole underlying socket send buffer."

This will surely be true if the buffer sizes are the same. They 
recommend making the socket buffer at least 1 byte bigger.

cheers

andrew



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