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Re: [lwip-users] TCP bandwidth limited by rate of ACKs


From: Mason
Subject: Re: [lwip-users] TCP bandwidth limited by rate of ACKs
Date: Wed, 12 Oct 2011 18:31:56 +0200
User-agent: Mozilla/5.0 (Windows NT 5.1; rv:7.0.1) Gecko/20110928 Firefox/7.0.1 SeaMonkey/2.4.1

Bill Auerbach wrote:

> That 7.4% for memcpy is a direct hit on throughput.  You're seeing a
> breakdown of total CPU time.  How much of that 7+% for memcpy comes out of
> the total time used by lwIP?  I think you'll find that to be a much larger
> hit and a large contributor to lower bandwidth.

Bill,

IMHO, the elephant in the room is task-switching, as correctly
pointed out by Kieran.

Assuming that every memcpy were lwip-related, and that I could
get rid of them (which I don't see how, given Simon's comments)
the transfer would take 478 instead of 516 seconds.

I.e. 58.6 Mbit/s instead of 54.3 Mbit/s

Not much of an improvement, IMHO.

Regards.



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