topic Re: ana/sys sho proc/chan in Operating System - OpenVMS

ana/sys sho proc/chan

Maurizio Savoia — Wed, 03 May 2006 03:57:52 GMT

How do i get to know the number of open channels of each and every running process? Using "analyze/system show proc/channel" is impractical on systems where a huge number of processes is running. Is there a way to get this information from a C program?

Re: ana/sys sho proc/chan

Ian Miller. — Wed, 03 May 2006 04:17:38 GMT

You could loop through all processes and use $GETJPI.
$GETJPI item FILCNT will give you open file quota remaining to subtracting this from FILLM
will give you number of files. However this does not count channels open to devices not files e.g terminals and mailboxes.

What problem are you trying to solve?

Re: ana/sys sho proc/chan

Volker Halle — Wed, 03 May 2006 04:23:22 GMT

Maurizio,

you can send the SDA output to a file:

$ ANAL/SYS
SDA> SET OUT x.x
SDA> SHOW PROC/CHAN ALL
SDA> EXIT

$ SEA x.x total

Like Ian said, what is your problem ?

Volker.

Re: ana/sys sho proc/chan

Jeff Chisholm — Thu, 04 May 2006 09:48:29 GMT

Volker's answer is the best, sending the output from
SDA> sh proc/chan all
to a file, but it depends on the pageable CCB area being in memory for each process. Not likely on a busy system.

Usually when someone asks this question, they're attempting to see how many channels are being used system-wide, their (incorrect) assumption is that CHANNELCNT is per system rather than per process.

Why do you need a total?

Re: ana/sys sho proc/chan

Ian Miller. — Thu, 04 May 2006 12:38:59 GMT

Jeff, as SDA sends a kernal AST to the target process to obtain the ccb table then I don't think it being pageable is an issue.

The issue is why does Maurizio want this information?

Re: ana/sys sho proc/chan

Jeff Chisholm — Thu, 04 May 2006 12:45:29 GMT

You're right, thanks. I've just gone looking for channels in too many crash dumps. Same SDA, different context.

Re: ana/sys sho proc/chan

Maurizio Savoia — Fri, 05 May 2006 06:26:22 GMT

The reason why I need this info is that some ACMS servers behaved badly; one of the hypothesis made by our development team was that the channelcnt parameter was underestimated, so I needed a per-process total of the number of I/O channel being used by the server processes. I adopted the "SDA> sho proc/chan all" solution to monitor the number of channels in use.

Re: ana/sys sho proc/chan

Ian Miller. — Fri, 05 May 2006 08:06:50 GMT

The memory cost of increasing CHANNELCNT is very low (but does need a reboot) so it may be worth increasing it anyway.