From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Axel Waggershauser" <awagger(at)web(dot)de> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Low throughput of binary inserts from windows to linux |
Date: | 2006-12-12 16:33:20 |
Message-ID: | 4101.1165941200@sss.pgh.pa.us |
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Lists: | pgsql-performance |
"Axel Waggershauser" <awagger(at)web(dot)de> writes:
> On 12/12/06, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I think this almost certainly indicates a Nagle/delayed-ACK
>> interaction. I googled and found a nice description of the issue:
>> http://www.stuartcheshire.org/papers/NagleDelayedAck/
> In case I was mistaken, this explanation makes perfectly sens to me.
> But then again it would indicate a 'bug' in libpq, in the sense that
> it (apparently) sets TCP_NODELAY on linux but not on windows.
No, it would mean a bug in Windows in that it fails to honor TCP_NODELAY.
Again, given that you only see the behavior at one specific message
length, I suspect this is a corner case rather than a generic "it
doesn't work" issue.
We're pretty much guessing though. Have you tried tracing the traffic
with a packet sniffer to see what's really happening at different
message sizes?
regards, tom lane
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