[lwip-users] Re: tx badnwidth

[Chen]

http://www.dataq.com/chen/lwip_tx.zip
is the capture file you asked for.

 From the capture, you can see the tx frequency drops dramatically:
100-byte payload: tx 631 packets per second, with packet sizes mostly in 100 and 700 bytes
2048-byte payload: 5 packets per second, and the packet sizes are between 690 to 1460 bytes

For the failed payload, like 500-byte payload, the tx frequency is similar to 2048-byte payload and the capture simply ends with the ACK from the PC, way before lwIP finish the tx.

At 12:00 PM 3/4/2009, you wrote:

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Today's Topics:

   1. Re: tx badnwidth (Chen)
   2. Re: Re: tx badnwidth (Kieran Mansley)
   3. Re: tx badnwidth (Chen)
   4. Re: Re: tx badnwidth (Kieran Mansley)


----------------------------------------------------------------------

Message: 1
Date: Wed, 04 Mar 2009 09:27:02 -0500
From: Chen <address@hidden>
Subject: [lwip-users] Re: tx badnwidth
To: address@hidden
Message-ID: <address@hidden>
Content-Type: text/plain; charset="us-ascii"

Sorry, forgot to include the result:

payloadsize=100, about 6 seconds
Payloadsize=200, about 3 seconds
payloadsize=400, never finish
payloadsize=500, never finish
payloadsize=1000, 3 minutes
payloadsize=2048, over 3 minutes

 >>>>>>>>>>>

Just a tight loop after the connection:

char dummy_data[2048];
total=10000000;
count=0;
do{
     l=lwip_send(clientfd, dummy_data, payloadsize, 0);
     count =count+l;
}while (count<total)

Just try different payloadsize, for example, 100, 500, 1000, 1500, 2000,
and you should see the result.


From:   Francois Bouchard
Subject:        Re: [lwip-users] Re: lwip-users Digest, Vol 67, Issue 6
Date:   Tue, 3 Mar 2009 14:59:43 -0500

Weird,
How long for a payload of... let's say 1400 bytes?
How do you measure/calculate the Bandwidth?

 >>>>>>>>>>>>


The TCP's tx bandwidth is greatly affected by the size of payload for
lwip_send.

My test is to send out 1000000 bytes of data as fast as possible (via TCP
connection, such as telnet)

If payload is 100 bytes, it takes only a few seconds to send out all the
data. If the payload is 2048, it takes a loooooooooooong time

Any comment?


>Subject: Re: [lwip-users] Re: lwip-users Digest, Vol 67, Issue 5
>To: Mailing list for lwIP users <address@hidden>
>Message-ID: <address@hidden>
>Content-Type: text/plain
>
>On Tue, 2009-03-03 at 09:05 -0500, Chen wrote:
>
> > 2) When I lwip_send too much data, the program actually crashes --- I
> > will investigate   more on the cause
>
>Thanks for investigating - it should work fine.  More details of what
>goes wrong, and what you do to cause it to go wrong would help.
>
>Kieran

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Message: 2
Date: Wed, 04 Mar 2009 14:32:39 +0000
From: Kieran Mansley <address@hidden>
Subject: Re: [lwip-users] Re: tx badnwidth
To: Mailing list for lwIP users <address@hidden>
Message-ID: <address@hidden>
Content-Type: text/plain

On Wed, 2009-03-04 at 09:27 -0500, Chen wrote:
> char dummy_data[2048];
> total=10000000;
> count=0;
> do{
>     l=lwip_send(clientfd, dummy_data,payloadsize, 0);
>     count =count+l;
> }while (count<total)

Can you check that lwip_send is not returning an error?  The value
returned by lwip_send will either be the size sent if l > 0, or an error
if l < 0.  This could explain why things go badly wrong for you.

Kieran





------------------------------

Message: 3
Date: Wed, 04 Mar 2009 11:17:03 -0500
From: Chen <address@hidden>
Subject: [lwip-users] Re: tx badnwidth
To: address@hidden
Message-ID: <address@hidden>
Content-Type: text/plain; charset="us-ascii"

I checked before, and caught no error

When payloadsize=400, Wireshark shows the ACK from PC to the last packet
from lwIP, and lwIP simply stops there

When payloadsize=1000, the packet frequency is much much slower than the
smaller payload

 >>>>

Can you check that lwip_send is not returning an error?  The value
returned by lwip_send will either be the size sent if l > 0, or an error
if l < 0.  This could explain why things go badly wrong for you.

Kieran
 >>>>

Sorry, forgot to include the result:

payloadsize=100, about 6 seconds
Payloadsize=200, about 3 seconds
payloadsize=400, never finish
payloadsize=500, never finish
payloadsize=1000, 3 minutes
payloadsize=2048, over 3 minutes

 >>>>>>>>>>>

Just a tight loop after the connection:

char dummy_data[2048];
total=10000000;
count=0;
do{
     l=lwip_send(clientfd, dummy_data, payloadsize, 0);
     count =count+l;
}while (count<total)

Just try different payloadsize, for example, 100, 500, 1000, 1500, 2000,
and you should see the result.


From:   Francois Bouchard
Subject:        Re: [lwip-users] Re: lwip-users Digest, Vol 67, Issue 6
Date:   Tue, 3 Mar 2009 14:59:43 -0500

Weird,
How long for a payload of... let's say 1400 bytes?
How do you measure/calculate the Bandwidth?

 >>>>>>>>>>>>


The TCP's tx bandwidth is greatly affected by the size of payload for
lwip_send.

My test is to send out 1000000 bytes of data as fast as possible (via TCP
connection, such as telnet)

If payload is 100 bytes, it takes only a few seconds to send out all the
data. If the payload is 2048, it takes a loooooooooooong time

Any comment?


>Subject: Re: [lwip-users] Re: lwip-users Digest, Vol 67, Issue 5
>To: Mailing list for lwIP users <address@hidden>
>Message-ID: <address@hidden>
>Content-Type: text/plain
>
>On Tue, 2009-03-03 at 09:05 -0500, Chen wrote:
>
> > 2) When I lwip_send too much data, the program actually crashes --- I
> > will investigate   more on the cause
>
>Thanks for investigating - it should work fine.  More details of what
>goes wrong, and what you do to cause it to go wrong would help.
>
>Kieran

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Message: 4
Date: Wed, 04 Mar 2009 16:40:26 +0000
From: Kieran Mansley <address@hidden>
Subject: Re: [lwip-users] Re: tx badnwidth
To: Mailing list for lwIP users <address@hidden>
Message-ID: <address@hidden>
Content-Type: text/plain

On Wed, 2009-03-04 at 11:17 -0500, Chen wrote:
> I checked before, and caught no error
>
> When payloadsize=400, Wireshark shows the ACK from PC to the last
> packet from lwIP, and lwIP simply stops there
>
> When payloadsize=1000, the packet frequency is much much slower than
> the smaller payload

If you have packet captures of cases where it works, and cases where it
fails, it would be very helpful to share them here!

Kieran





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