OS suddenly VERY busy

[Mikhail T.]

Hello!

After a couple of huge tarball extracts (`make extract' in jdk14 and jdk15)
I noticed, things are a little slower. During the extracts, the mouse was
moving with visible jerks. Indeed, the system seems VERY busy:

   11 users    Load  1.18  1.52  1.40                  Jul 20 00:14

Mem:KB    REAL            VIRTUAL                     VN PAGER  SWAP PAGER
        Tot   Share      Tot    Share    Free         in  out     in  out
Act 1060360  105932  1341624   145252  151016 count
All 1750432  115908  8911872   174532         pages
                                                          zfod   Interrupts
Proc:r  p  d  s  w    Csw  Trp  Sys  Int  Sof  Flt        cow    1277 total
     4     1146      1819  345 443k 1640  672      266572 wire      4 irq1: atkb
                                                  1204008 act    1004 irq0: clk
84.7%Sys   0.0%Intr 15.3%User  0.0%Nice  0.0%Idl   241536 inact       irq6: fdc0
|    |    |    |    |    |    |    |    |    |      62232 cache   128 irq8: rtc
==========================================>>>>>>    88784 free        irq9: acpi
                                                          daefr   113 irq12: psm
Namei         Name-cache    Dir-cache                     prcfr       irq15: ata
    Calls     hits    %     hits    %                     react       irq16: ahc
     3030     3030  100                                   pdwak    26 irq17: pcm
                                                          pdpgs       irq18: fwo
Disks   da0   cd0   cd1 pass0 pass1 pass2                 intrn       irq19: ohc
KB/t   4.00  0.00  0.00  0.00  0.00  0.00          218912 buf         irq27: skc
tps       2     0     0     0     0     0              21 dirty     2 irq29: cis
MB/s   0.01  0.00  0.00  0.00  0.00  0.00          100000 desiredvnodes
% busy    0     0     0     0     0     0           92043 numvnodes

The machine is idle and is not doing anything in user-space according to both
top and vmstat's "pigs" display.

Yet it is noticably slower. Trying to compile something pushes the load above
2. What is it doing?

This is a single-CPU Opteron running:

	FreeBSD 5.4-STABLE #0: Fri Jun 10 09:11:30 EDT 2005 amd64

The box has 2Gb of RAM, but NO SWAP.

Any ideas? Thanks!

	-mi