High system time on dual processor system ?

High system time on dual processor system ?

Post by Dirk Kleinhesseli » Thu, 23 Oct 1997 04:00:00



    I have a dual Pentium Pro machine from TriStar with 128MB ram.  I
installed Red Hat 4.2 and built a SMP kernel, which finds the second
processor -- I can see it in /proc.  I've been benchmarking this machine
against a Linux/Alpha, DEC/Alpha and SGI IRIX system.  We are running
FORTRAN code - I'm using g77 to compile on the dual Ppro and timing using
/usr/bin/time program
    I'm getting system times that are incredibly large on this system as
compared to any of the other machines, as well as single processor Intel
machines.  If the system time was 1/10th of the user time, it would be
OK -- the machine would  be fast, but under certain compilations, the
system time is even larger than the user time.  Anyone know anything about
this ?  Below are some sample timings:

       compiler options        user time        system time
         No options             24.71             106.17
           -O2                  28.67              45.25
           -O2 -ffast-math      15.43              12.68
-O2 -ffast-math -funroll-loops  22.43               9.78
-O4 -ffast-math -funroll-loops  17.46              10.65

On other machines, system times are typically  less than 1 sec (the above
units).

Dirk

 
 
 

1. High system CPU% in dual CPU System

I'm experiencing very high system CPU% indications on my new dual
Pentium III machine (SuSE Linux 7.1, Kernel 2.4.4-SMP):

  12:26am  up 1 day,  8:34,  9 users,  load average: 1.44, 2.74, 3.26
116 processes: 113 sleeping, 3 running, 0 zombie, 0 stopped
CPU0 states: 19.2% user, 32.0% system,  0.0% nice, 48.2% idle
CPU1 states: 20.4% user, 40.1% system,  0.0% nice, 38.3% idle
Mem:   512180K av,  498144K used,   14036K free,       0K shrd,  145360K buff
Swap: 1024120K av,    8504K used, 1015616K free                   39976K cache

   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
20308 root       9   0 21056  20M  1744 S     2.7  4.1   6:14 X
30471 capicall  12   0  1020 1020   772 R     0.7  0.1   0:36 top
   594 root       9   0   628  628   480 S     0.5  0.1   6:59 nscd
22072 ingo      17   0  1484 1484   576 R     0.5  0.2   0:00 ps
   596 root       9   0   628  628   480 S     0.3  0.1   6:36 nscd
22467 ingo       9   0  3940 3940  2812 R     0.3  0.7  11:03 gkrellm
22978 ingo       9   0  1380 1380  1132 S     0.3  0.2   0:04 ssh
   597 root       9   0   628  628   480 S     0.1  0.1   6:31 nscd
   598 root       9   0   628  628   480 S     0.1  0.1   6:35 nscd
22071 ingo      17   0  1036 1036   852 S     0.1  0.2   0:00 sh
...

After the initial Installation everything was fine - it must be
caused by some additonal package, but I have no clue.

What can I do to find out what the CPUs are doing during "system" time?

--

Ingo

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