Console Process Priority Issue

[Andrew Dutton]

We have a major conversion for our ERP coming up and the DBA is running the conversion from the console. This console is a lunix box connecting to the serial port of an RP4440 running 11.11 The process ran fine in a remote session but when it ran on the console it slowed down. It would run at about 3-4% cpu utilization and be dog slow... but tusc showed me it did still run... then if the DBA would hit a key on the menu it would jump up to 90% cpu, start flying... and then slowing slow down again.

Something is very wierd here... why would it matter if the console was used? It is a TTY based gui that the command runs in.

thanks

[Steven E. Protter]

Shalom,

The rp4440 has a GSP card, console services can be run from there you can run console services.

SEP

[Andrew Dutton]

Yes but if I am not mistaken I need to assign and IP to it... this way I have all my boxes on a single console server. Either way do you think it has anything to do with the issue though?

[A. Clay Stephenson · Accepted solution]

There is something I don't understand. "if the DBA would hit a key on the menu" implies that this program is waiting for keyboard input OR is polling the controlling terminal for input. If the program is polling for possible keyboard input rather than waiting for keyboard input then I can imagine a scenario in which using the console (a true tty port) and another port (a network pseudo tty port) would behave differently although it would not adjust process priority per se. I suspect that an ioctl is being used where VMIN=0 and VTIME=0 which will cause the polling to run like crazy rather than VMIN=0 and VTIME=1. Of course, a better way to handle input in a scenario where threads or processes are running asynchronously, is to detect signals rather than polling.

[Andrew Dutton]

From what you said Clay... it would seem to be an issue from the vendor with the applicaiton and not something I can help with from the system side? Or is there something I can help with?

If we did start it from a remote shell... is there anyway to disconnect and then reconnect later from a different machine to the same process? The process is outputting to the screen the entire time.

[A. Clay Stephenson]

There is no practical way to disconnect a controlling terminal and reconnect later.

[A. Clay Stephenson]

"The process is outputting to the screen the entire time."

This model is contrary to the common UNIX convention of "no news is good news" unless stdout is actually used to write data that are subsequently used by other processes. In your case, it seems to be sending "all is well" or "1435 records processed" to stdout which is about as useful as tits on a boar hog.

[Andrew Dutton]

As I understand it, the process will require input at some later time in the process but not for hours until it is complete. they should have it run as a process and then log to a file that they will tail or something along those lines... thanks