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Re: ethernet performance <TCPIP guru question>
- From: Gary Thomas <gthomas at redhat dot com>
- To: Stephen Polkowski <stephen at centtech dot com>
- Cc: eocs <ecos-discuss at sources dot redhat dot com>
- Date: 24 Apr 2002 19:39:51 -0600
- Subject: Re: [ECOS] ethernet performance <TCPIP guru question>
- References: <3CC74F46.1050502@centtech.com>
On Wed, 2002-04-24 at 18:35, Stephen Polkowski wrote:
> Hello,
>
> I've been working on a simple ftp server for ECOS. I have it up
> and working on the intel pc using the 82559 ethernet card. I'm also
> using redboot to load my application over the ethernet.
>
> When I ftp a file to my server application I seeing some really
> slow ethernet speeds. I have a 100Mb ethernet running on a 2Ghz Pentium
> IV. So, my system should be fast enough to handle the data. I'm
> getting about 65k bytes a second transfer rate. I should be get getting
> something close to 10M bytes a second. What's the problem?
>
I've tested TCP operations with eCos, using 100Mb interfaces, and I get
transfer rates of around 8Mbytes/sec (Linux host, sending data to an
eCos application which simply sinks the data).
> I did a tcpdump from my Linux machine. I've noticed two things.
> First, the TCP window size in ECOS isn't sliding during the transfer.
> This might be confusing the sender, I'm not sure. Also, I see a burst
> of data packets and ACKS from ECOS which appear good. Then all of a
> sudden, ECOS starts to ACK to the same packet over and over. After a
> few more acks, the sequence resumes. Is this normal? Does this explain
> the slow network performance?
>
> Here's the dump of the burst sequence running into the ACK sequence.
>
> Thanks.
>
Which IP address is the eCos side?
I assume from your description that the eCos "server" program is being
sent the data. What does it do with it when it arrives?
> 1.1.1.2.55961 > 1.1.1.3.ftp-data: . 1507369:1508817(1448) ack 1 win 5792
> 1.1.1.2.55961 > 1.1.1.3.ftp-data: . 1508817:1510265(1448) ack 1 win 5792
> 1.1.1.2.55961 > 1.1.1.3.ftp-data: . 1510265:1511713(1448) ack 1 win 5792
> 1.1.1.2.55961 > 1.1.1.3.ftp-data: . 1511713:1513161(1448) ack 1 win 5792
> 1.1.1.2.55961 > 1.1.1.3.ftp-data: P 1513161:1514609(1448) ack 1 win 5792
> 1.1.1.3.ftp-data > 1.1.1.2.55961: . ack 1513161 win 18824
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