Hi Juan:
	I'm going to point people back to the networking topic for a
bit.  I got around to trying out your test code and I found some flaws
that need to be corrected. 

	Robert.

-----Original Message-----
From: Juan Manuel Placco [mailto:community-noreply@qnx.com] 
Sent: Wednesday, December 03, 2008 1:07 PM
To: ostech-core_os
Subject: 6.3 vs 6.4 uK message passing comparison (same node)

Hi, 

As Robert suggest I'm moving to this forum with my question.

This cames from a large discussion in:

http://community.qnx.com/sf/go/projects.networking/discussion.technology
.topc5048 

Robert wrote:
>>I'm a bit surprised that the comparison shows that much  improvement 
>>with large message transfer sizes as well.
>> I would have expected the improvements to be most noted  for small 
>>messages (in which the kernel overhead dominates  the message pass) as

>>opposed to the large messages (which should be dominated by the actual

>>time to do the copy).
>> I think that you might want to post this information in one of  the 
>>forums on the OS project to get a better explanation.
>> I'm not sure of the kernel optimizations which were introduced  in 
>>6.4.0 which would affect message passing.
>>	Robert.

The thing is a have a benchmark test comparing message passing (form
different sizes) in the SAME node, in 6.3 and in 6.4 installations (the
same machine with 2 partitions).

I was expecting the same results as Robert mention, but I'm still
surprised and wondering what's behind de scene... How can 6.4 be much
faster moving data from client to server address space? It's just
something very similar to a memmove, isn't it? And this is, as I suppose
almos an assembly level function with lot of work for DMA and RAM
memory.

I attach the results in an excel file.

I will be very thankful if they can help me to understand this behavior
difference between 6.3 and 6.4 kernel!

Regards,
Juan Manuel

_______________________________________________
OSTech
http://community.qnx.com/sf/go/post17865