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Forum Topic - tcp/ip packet to application latency: (7 Items)
   
Update
Mike Srdanovic
04/01/2011 5:56 PM
post84532
tcp/ip packet to application latency   
General qustion to all: Are there any stats or reviews available that would give me some figures around the general tcp/
ip packet latency I could expect within my QNX application? I realize that this is a large topic and a loaded question, 
but what I'm trying to get the sense of is the general expected data latency on QNX from arival on the NIC to my 
application via recv(), given a "fast" machine.

Thanks in advance
Mike
Jeevan Mathew(deleted)
04/02/2011 6:28 AM
post84536
AW: tcp/ip packet to application latency   
I do not think that this kind of stats are available. Also the transport of the information can be preempted along all 
the way up to your application by any higher prior event. You would have to cut down your system just having your app 
and the stack and do the measurement yourself to be able to compare it with whatever.

My 2 cents.
-Jeevan

----- Originalnachricht -----
Von: Mike Srdanovic [mailto:community-noreply@qnx.com]
Gesendet: Friday, April 01, 2011 05:56 PM
An: technology-networking <post84532@community.qnx.com>
Betreff: tcp/ip packet to application latency

General qustion to all: Are there any stats or reviews available that would give me some figures around the general tcp/
ip packet latency I could expect within my QNX application? I realize that this is a large topic and a loaded question, 
but what I'm trying to get the sense of is the general expected data latency on QNX from arival on the NIC to my 
application via recv(), given a "fast" machine.

Thanks in advance
Mike




_______________________________________________

Technology
http://community.qnx.com/sf/go/post84532
Mike Srdanovic
04/02/2011 10:11 AM
post84538
Re: AW: tcp/ip packet to application latency   
Jeevan,

This is essentially what I have, a single dedicated app on the host with nothing more than the network stack being 
utilized once the app is running. The app currently runs on a different OS and I'm trying to determine the expected 
improvement porting to QNX (i certianly expect some). The app has "chat" functionality i.e. it's sole purpose is to 
receive network packets via UDP and communicate to other servers via tcp/ip. The communication latency (both UDP and via
 TCP) is of utmost importance and am trying to minimize this value.

Thank,
Mike
Patrik Lahti
04/03/2011 12:29 PM
post84541
Re: AW: tcp/ip packet to application latency   
Sounds like you should not do this measurement using your "app" but 
rather using a (known good) latency test software.

Good luck!
/P

On 11-04-02 10:11 AM, Mike Srdanovic wrote:
> Jeevan,
>
> This is essentially what I have, a single dedicated app on the host with
> nothing more than the network stack being utilized once the app is
> running. The app currently runs on a different OS and I'm trying to
> determine the expected improvement porting to QNX (i certianly expect
> some). The app has "chat" functionality i.e. it's sole purpose is to
> receive network packets via UDP and communicate to other servers via
> tcp/ip. The communication latency (both UDP and via TCP) is of utmost
> importance and am trying to minimize this value.
>
> Thank,
> Mike
>
>
>
>
>
> _______________________________________________
>
> Technology
> http://community.qnx.com/sf/go/post84538
>
Mike Srdanovic
04/04/2011 7:58 AM
post84553
Re: AW: tcp/ip packet to application latency   
Yes, thanks for the suggetion and I've thought of that approach as well. Is there a standard network test tool set 
available for qnx?

Mike
Patrik Lahti
04/04/2011 8:22 AM
post84558
Re: AW: tcp/ip packet to application latency   
There are, e.g. iperf/netperf/etc, and we use them all them all the 
time, but they measure the entire path between two hosts. And from your 
original description, that's not what you want to measure. You could 
make a custom driver just for measuring exactly what you want, or maybe 
use loopback, or custom kernel event trace...

On 04/04/2011 07:58 AM, Mike Srdanovic wrote:
>
> Yes, thanks for the suggetion and I've thought of that approach as 
> well. Is there a standard network test tool set available for qnx?
>
> Mike
>
>
>
> _______________________________________________
>
> Technology
> http://community.qnx.com/sf/go/post84553
>
Mike Srdanovic
04/04/2011 7:53 PM
post84594
Re: AW: tcp/ip packet to application latency   
thanks to everyone for your response and suggestions. Glad to hear that the standard tools are available for QNX and I 
look into putting together a custom test as a first step.

Mike

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