topic Re: ioctl system calls in Operating System - HP-UX

ioctl system calls

Dave Burton_5 — Thu, 05 May 2005 11:07:40 GMT

I've got a spinning WebLogic java process on an HP server. When I look in the system calls screen, I find millions of ioctl commands consuming most of the CPU cycles.

What options do I have to work out what files these millions of ioctl calls are trying to use? Where can I get more detailed information on what ioctl is all about anyway?

Re: ioctl system calls

rick jones — Fri, 06 May 2005 11:08:00 GMT

grab a copy of tusc - there is one on ftp.cup.hp.com under dist/networking/tools/

or you can search on tusc on www.hp.com

Re: ioctl system calls

A. Clay Stephenson — Fri, 06 May 2005 11:25:10 GMT

Tusc should be your weapon of choice for this. The bad news is that ioctl() is, by definition, driver specific. It is one of the few system calls where exactly the same arguments to the system call can produce very different behaviors. You have to tie the 1st argument (the file descriptor) to the actual device. For example, if you see that the 1st argument to ioctl is 5, you need to find the last system call (e.g. open, creat, pipe) that opened fdes 5 and then refer to the man pages that are associated with that device. You should also be aware the fdes 5 might be reused many times so simply finding an open() system called that returns 5 is not enough; you need to find the one that imediately precedes the ioctl() of interest.