OS task causing 50mS stall every 60 sec.

[bwolfe]

I have a Netburner 5270B that I'm using in an application that involves reading data from an external hardware FIFO and periodically sending it out in a UDP data-gram. I had an issue where periodically my FIFO would overflow. I created a simple program that toggled a pin in an endless loop and found expected jitter due to OS background tasks of a few uS when monitoring with a scope. I also found a periodic stall of 80uS and most disturbingly a stall of 50mS every 60 Sec. I used task monitor and found a task called TCPD with a priority of 40 being called every 1200 or so ticks. That comes out to about 60 sec. so I think it's the culprit.

Question is what is that task and is there a way to kill it or cause it to take less than 50mS away from user main at any one time. It would be acceptable to lose less time more often for example 5 mS every 6 sec. As it stands my FIFO is not large enough to ride through the 50mS stall.

Thanks in advance for any help.

[sblair]

TCPD is the TCP daemon. What NNDK version are you using? There have been a few TCP latency bugs recently that have been discussed in release notes. Not sure if what you are seeing specifically relates to one those but knowing what version you are on is probably the first step.

Scott

[bwolfe]

Thanks Scott. I was using NNDK version 2.6.2. I looked up the release notes and saw there was a bug. After updating to the latest version (2.7.0) the problem is fixed! Thanks again.

-Brian

[sblair]

I've learned to watch the release notes pretty carefully just to stay abreast of potential issues. I avoid running the beta releases here unless it is absolutely critical, but I keep track of the release notes just to be aware of issues in the current stable release they might have fixed in the next beta that I'm not aware of yet. I tend to wait a couple months after a release has been marked as stable before updating to it.

Glad it turned out to be an easy solution for you.

[dciliske]

Yup. I saw the subject and went, "Hmm... gotta be running an older version. I remember fixing that."

-Dan