RE: [lwip-users] Performance results

[John Taylor]

Leon,

I applied the ARP patch as per your posting.  It does speed up my ping
response time, but just *barely*.  The fix yields only a 0.5% to 1.0%
speed increase in ping response time.


-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf
Of Leon Woestenberg
Sent: Wednesday, February 04, 2004 9:33 AM
To: Mailing list for lwIP users
Subject: RE: [lwip-users] Performance results


Hello John,

pls. see my other msg. There may be an ARP
problem (where the ARP cache is only rarely correctly updated)
in 0.7 that may have caused the performance problem.

Not sure yet if this is the cause.
Anyway, I expect to fix this within two days.

Leon.

On Tue, 3 Feb 2004 01:09:59 -0500, "John Taylor"
<address@hidden> said:
> >From: address@hidden
> [mailto:lwip->address@hidden On
> Behalf Of Kieran >Mansley
> >
> >... but it does demonstrate that the stack can run fast (if you 
> >rip out all the slow bits!)
> 
> What are the "slow bits?"  
> 
> I am finishing up porting lwip to two Hitachi H8s eval boards
(edosk2674
> @33Mhz and esp-hbdb01 @20Mhz).  I noticed that lwIP had what appeared
to
> be a slow response time to pings (1.3 msec).  I thought at first it
was
> because of my debug environment, but I ran in "stand-alone" mode and
the
> times did not change.  
> 
> Then I thought, well maybe its how I implemented my low-level Ethernet
> driver.  So I ran my port of Adams Dunkels' uIP on the same boards.
My
> ports of uIP and lwIP have identical low-level drivers - with the only
> exception being that lwIP uses PBUFs and uIP has a single global
buffer.
> Okay, there is more indirection with the PBUFs than with an absolute
> address, but the ping times for uIP are .8msec.  The ping times for
lwIP
> are 65% SLOWER than uIP.  I find it hard to believe this large
> difference is due to PBUFs vs. a static buffer.  Both boards have a
> 16bit MCU with 32bit general purpose registers and the same compiler
and
> same RTOS was used for all of the test apps. The test apps for both
> stacks are web-servers with no network traffic except for the pings.
> 
> One last caveat.  My port lwIP is not finished.  I still have bug
where
> the TCP "ack" number gets out-of-sync and effectively stalls some of
the
> connections.  However, I can flood ping the board and not loose a
single
> packet.
> 
> 
> Is a 1.3msec ping response time reasonable for lwIP or have I screwed
> something up in my port?
> 
> 
> 
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