Subject: Peculiar interrupt statistics
To: None <port-sparc64@netbsd.org>
From: Jarle Greipsland <jarle@uninett.no>
List: port-sparc64
Date: 10/11/2001 11:55:40
Hi,
I just noticed something about the interrupt counts shown by
systat that seemed a bit strange, at least to me. An excerpt
from the "vmstat" display shows:
3 users Load 2.05 2.85 3.08 Thu Oct 11 11:53:15
memory totals (in KB) PAGING SWAPPING Interrupts
real virtual free in out in out 1099 total
Active 135016 135016 86672 ops 497 lev1
All 165488 165488 611328 pages 7 lev5
495 lev6
Proc:r d s w Csw Trp Sys Int Sof Flt 3 forks 100 clock
1 8 45 861 1512 1099 1691 1 fkppw
1 fksvm
24.8% Sy 0.0% Us 74.7% Ni 0.0% In 0.6% Id pwait
| | | | | | | | | | | relck
============-------------------------------------- rlkok
noram
Namei Sys-cache Proc-cache 32 ndcpy
Calls hits % hits % 30 fltcp
3732 3716 100 667 zfod
13 cow
Discs cd0 wd0 md0 32 fmin
seeks 42 ftarg
xfers 7 itarg
Kbyte 127 488 wired
%busy 1.4 pdfre
Notice the almost equal numbers for level1 and level6 interrupt.
I kept an eye on the display for some time during a kernel build,
and the maximum difference between these two numbers was less
than 10. I also noticed that the "wired count" in the vmstat
display was very close to the interrupt level1 and level6
interrupt counters.
What is the reason for this? Is this a double counting error?
Double interrupt posting error (or feature)? Bug in systat? Or
is this just the way it's supposed to be?
(This is on a Ultra 5 running -current from two days ago).
-jarle