High load (25% system) on 6450

Vsevolod Ilyushchenko simonf at cshl.edu
Tue Mar 19 11:31:01 CST 2002


Hi,

I am running stock 2.4.17 on a 6450. I have recently upgraded to 4 CPUs,
and soon after that I began to see high load. Today it varies from 5 to 8,
and it's not an accounting fluke - the system is very slow.

The maddening thing is that I cannot figure out what's causing it. Top does
not show any CPU-hogging programs. The only abnormal thing that I saw in
the sar output is consistently high system time percentage:

12:00:11 AM       CPU     %user     %nice   %system     %idle
12:10:00 AM       all      2.77      0.42     26.22     70.60
12:20:09 AM       all      2.47      0.01     25.80     71.72
12:30:00 AM       all      2.39      0.01     25.98     71.62
12:40:10 AM       all      2.48      0.01     25.74     71.77
12:50:24 AM       all      2.49      0.01     25.86     71.64

My suspicions are on SAS running some user batch programs. Most of the time
it's in the D state according to top, but since it constantly updates a
file in /var/tmp, it's not dead.

I see somewhat high disk activity on interrupt 17:

(from /proc/interrupts:
 17:   15878552   15873368   15886390   15879782   IO-APIC-level  aic7xxx
)

12:00:11 AM  CPU  i000/s  i001/s  i002/s  i014/s  i017/s  i018/s  i026/s
12:10:00 AM    0   25.16    0.00    0.00    0.00  199.71    0.00    1.74
12:10:00 AM    1   24.99    0.00    0.00    0.00  198.40    0.00    1.78
12:10:00 AM    2   25.34    0.00    0.00    0.00  202.26    0.00    1.77
12:10:00 AM    3   24.51    0.00    0.00    0.00  197.82    0.00    1.70
12:20:09 AM    0   24.96    0.00    0.00    0.00  198.46    0.00    1.16
12:20:09 AM    1   24.95    0.00    0.00    0.00  198.56    0.00    1.16
12:20:09 AM    2   24.81    0.00    0.00    0.00  198.47    0.00    1.15

But this disk activity may just be the indicator of SAS writing its file.

Here is free output showing that memory is fine:

             total       used       free     shared    buffers     cached
Mem:       3996696    3890456     106240          0      75036    3300428
-/+ buffers/cache:     514992    3481704
Swap:       530104      32792     497312

I will be very grateful for any suggestions.

Simon
-- 
Simon (Vsevolod ILyushchenko)   simonf at cshl.edu   
http://www.simonf.com          simonf at simonf.com 

"A man who feels himself a citizen of the world whose 
loyalty is to the human race and to life, rather than 
to any exclusive part of it; a man who loves his country 
because he loves mankind, and whose judgement is not 
warped by tribal loyalties." Erich Fromm




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