Re: DESCHALL runs wild when run under nohup?

Dave Ahn (ahn@indigo2.rad.bgsm.edu)
Mon, 5 May 1997 15:52:26 -0400 (EDT)


> BOFH> When I came in this morning I found the UNIX host running very
> BOFH> slowly. The culprit was your proccess "deschall-sparc
> BOFH> keymaster.verser.frii.com", which had been running since 11:40 PM
> BOFH> Sunday. When I discovered it, it had used a tremendous amount of
> BOFH> processor time and was still growing rapidly. I killed it off at
> BOFH> about 8:35 AM.
>
> I tend to doubt this. What hasn't been stated is what the priority of
> the process was. Likely, he was looking at the process table, and saw
> something like
>
> cmcurtin 7987 11154 68 Apr 18 pts/4 23760:16 ./deschall-sparc keymaster

This is a common misconception. Priority of a process has no direct
relevance on the CPU time (above, 23760 minutes and 16 seconds of CPU time)
used by a process to accomplish an fixed sized task. If the above process
were nice'ed to -20 or to +20, it would still use the same amount of CPU time
to make the same number of encryptions. It's that the amount of delta _real_
time (looking at your watch) can change, depending on the process priority
and the CPU load.

Obviously, the system administrator was looking at 'top' or some such
process info utility and watching the CPU seconds and minutes rise
every update or two, which happens when any CPU intensive application
is running.

Dave.

-- 
Dave Ahn,  ahn@vec.bgsm.edu             "When you were born you cried, and the
           ahn@indigo2.rad.bgsm.edu      world rejoiced.  Try to live your life
Virtual Endoscopy Center                 so that when you die you will rejoice,
Bowman Gray School of Medicine           and the world will cry."  -1/2 jj^2