Why some PC's look at PSH flag and some not?

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On Stack overflow I asked a question about programming around TCP and reading the contents of the TCP stream and now I just found the solution of it. Namely the PSH flag of TCP headers that needs to be set in fact. But now it is not set.
Now my question about this is, why do some PC's have fast TCP speed with devices that don't have the PSH flag set, and some PC's are slow? The PC's we noticed the differences are all Windows 7 (32 and 64 bit) so it cannot be related to the OS as far as I see. Can somebody explain me more about this issue?

TimVK

Posted 2012-06-08T08:06:58.837

Reputation: 111

Answers

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The push flag decreases your throughput efficiency to reduce latency a little. It is used to signal that no more data is to follow so buffers can be flushed and data forwarded to the other end's app without waiting for more data. The use of the PSH flag is determined by the data communications protocol (not by device, OS, or end-user configuration)

See this article

The reasons why one PC is faster than another are legion. I expect you'd have to test carefully and provide more details to get useful help on this.

RedGrittyBrick

Posted 2012-06-08T08:06:58.837

Reputation: 70 632

What are the things I can test to determine what's the problem? And what kind of details are useful for help? I was thinking in the way of drivers and or hardware that handles those messages differently? – TimVK – 2012-06-08T09:52:43.853

@TimVK: I'd expect handling of TCP PSH flag to be in OS TCP/IP stack code, not in Ethernet device drivers nor in hardware. This comment-box is too small to answer your follow-on questions. – RedGrittyBrick – 2012-06-08T11:12:43.113

Indeed you are right about the handling of TCP flags. That was just the first thing I thought of without thinking twice. – TimVK – 2012-06-08T11:21:28.420

Asked: 2012-06-08T08:06:58.837

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Active: 2012-06-08T09:30:41.687