New REQUIRED version of C++ libraries

[virtuald]

Originally Posted by Mike Copioli

Brad,

Thank you for this update.

What is the observed robot behavior that this fixes?

A diff can be seen here. Looks like the big changes are disabling TCP_NODELAY, requiring a newer version of the Jaguar firmware, and fixing the way it searches for entries.

[taichichuan]

Originally Posted by virtuald

A diff can be seen here. Looks like the big changes are disabling TCP_NODELAY, requiring a newer version of the Jaguar firmware, and fixing the way it searches for entries.

Hmm... Disabling TCP_NODELAY. That will add several ms of latency to the link. Was there a problem in polling the socket connection that required this? Just curious because in almost 30 years of working with VxWorks, you typically want to *add* TCP_NODELAY to reduce communicaitons latency rather than remove it.

TIA,

Mike

[Greg McKaskle]

I haven't seen the code, but my understanding is that at last some of the writes were done a byte at a time -- likely with the iostream ++ syntax. That plus the no-delay resulted in lots of packets that made the router unhappy.

I agree with your comment about no-delay. I'd expect the latency to be around as much as 100ms.

Greg McKaskle

[taichichuan]

Originally Posted by Greg McKaskle

I haven't seen the code, but my understanding is that at last some of the writes were done a byte at a time -- likely with the iostream ++ syntax. That plus the no-delay resulted in lots of packets that made the router unhappy.

I agree with your comment about no-delay. I'd expect the latency to be around as much as 100ms.

Greg McKaskle

Hi Greg,

Yeah, I could believe that. Given the number of packets in normal driver station comms, I could see that there's likely a fair amount of 802.3x flow control packets if the switches are being overrun. However, this sounds like a hack. VxWorks is a very deterministic O/S. If it's resorting to very short payloads, it's likely because there's a resource starvation going on someplace and this is a quick hack to get past the problem. I've seen multiple places in WPILib that look like desktop folks trying to understand operating in real-time -- unsuccessfully. But, they keep introducing additional layers of abstraction hoping to make things easier. However, abstraction layers have a price. I suspect that this small payload issue is one of those prices.

How much longer are we using this control system? There are many ways to improve performance on the 'bot without losing the 3 language support. I've been a long time user and developer on VxWorks. But the reality is that WRS, really isn't doing much to promote the use of VxWorks on the 'bot. They're really missing an opportunity, IMHO.

Thanks,

Mike

[sircedric4]

I am getting everything ready for our regional this week and I have installed this required update and rebuilt my code.

Is there some way I can confirm that I have the workbench update installed so I don't have to panic on Thursday? Is there a version number somewhere I can check?

In the past I sometimes had trouble with the self installers working and I just want to confirm I am ready to go. How would the inspectors check it?

[Jefferson]

Originally Posted by sircedric4

Is there some way I can confirm that I have the workbench update installed so I don't have to panic on Thursday? Is there a version number somewhere I can check?... How would the inspectors check it?

You can check by navigating to:
C:\WindRiver\WPILib
You should have a .zip file in that folder of the format: WPILibC++SourceYYYYMMDDrevXXXX. The XXXX should be 3622. I have not been to an event since this was released, but I believe the inspectors will check this same way.

[sircedric4]

Originally Posted by Jefferson

You can check by navigating to:
C:\WindRiver\WPILib
You should have a .zip file in that folder of the format: WPILibC++SourceYYYYMMDDrevXXXX. The XXXX should be 3622. I have not been to an event since this was released, but I believe the inspectors will check this same way.

Thank you, I have confirmed my computer is up to date.