suspending processes (kill -STOP)

[doelz at urz.unibas.ch]

In article <JIM.90Jun10225458 at baroque.Stanford.EDU>, jim at baroque.Stanford.EDU (James Helman) writes:
> 
> But the numeric computation is basically a parasitic use.  We'd like
> to be able to suspend computational jobs when running graphics.
> Nicing isn't enough, especially if the other jobs are pounding I/O.
> 
If you're root, do a 

# npri -h250 -p<pid>

and the process will literally die but execute always if there is nothing 
else to do. Because you presumably don't want to have anyone root priv, 
set up a cron script which greps the cpu choppers from the process table 
every hour. We did that, and since that time there is happy graphics 
computing while at least two steady number crunchers are powering at night. 

> 
> Is there any way to suspend a process under IRIX?


Use the call blockproc(2). There, you'll find the description to block 
a process. The call can be issued from both fortran and c . I don't 
think it to be great because you always need to remember to unblock the 
process again. Therefore, I use the schedctl(2) call as described 
above, which uses the following priorities (taken from 
/usr/include/sys/schedctl.h) : 

/* possible non-degrading priorities */

/* these priorities are higher than ALL normal user process priorities */
#define NDPHIMAX        30
#define NDPHIMIN        39

/* these priorities overlap normal user process priorities */
#define NDPNORMMAX      40
#define NDPNORMMIN      127

/* these priorities are below ALL normal user process priorities */
#define NDPLOMAX        128
#define NDPLOMIN        254


.. take care not to use PHI values, you'll kill your system... 

Good luck, 

Reinhard 

************************************************************************
    Dr. Reinhard Doelz            *     EAN     doelz at urz.unibas.ch
      Biocomputing                *     DECNET  48130::doelz
Biozentrum der Universitaet       *     X25     psi%46211142::embnet
   Klingelbergstrasse 70          *     FAX     x41 61 256760
     CH 4056 Basel                *     TEL     x41 61 253880 ext 888
************************************************************************


PS: 

If you get tired of all that, run dbx on the process you want to stop using 
the following command in the 'console' window:  

# dbx -p <pid> >& /dev/null & 

and you will have the process supended. If you log out the 
window manager, the console window dies, and therefore, the process is 
released again.