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Re: [lwip-users] TCP bandwidth limited by rate of ACKs
From: |
Kieran Mansley |
Subject: |
Re: [lwip-users] TCP bandwidth limited by rate of ACKs |
Date: |
Tue, 11 Oct 2011 16:18:42 +0100 |
On Tue, 2011-10-11 at 17:13 +0200, Mason wrote:
> > In this UDP test did you use lwIP to process the UDP traffic, or was
> it
> > just a test that interfaced directly to your driver?
>
> In the UDP test, any frame larger than 1500 bytes was
> not passed to lwip. The bogus ACK was sent directly
> from the RX context instead.
OK, I'm not at all surprised that there is a big difference between the
performance of that test, and the TCP performance you first measured.
In the TCP case using the sockets API, you have:
1) 2 copies in each direction (app to/from lwIP, lwIP to/from your
driver's buffer descriptors)
2) all the TCP protocol processing (which is probably not a big deal)
3) 2 context switches in each direction (driver to/from lwIP, lwIP
to/from app)
This is going to put a big dent in the throughput. You can avoid a lot
of that by using the raw lwIP API. If you have to stick with the
sockets API you may be stuck with relatively low throughput.
Kieran
- [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/10
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Simon Goldschmidt, 2011/10/10
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/11
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Kieran Mansley, 2011/10/11
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/11
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs,
Kieran Mansley <=
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/12
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Bill Auerbach, 2011/10/12
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/12
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, address@hidden, 2011/10/12
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/13
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, address@hidden, 2011/10/13
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/17
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, address@hidden, 2011/10/17
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Mason, 2011/10/18
- Re: [lwip-users] TCP bandwidth limited by rate of ACKs, Simon Goldschmidt, 2011/10/18