Hyperactive pagezero

[Ivan Voras]

On a very loaded web server (httpd processes are huge because PHP uses 
lots of shared memory) the pagezero process seems to constantly take up 
to 30% of CPU time (this is 2-CPU SMP machine):

   PID USERNAME  THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
    12 root        1 171   52     0K     8K RUN    0 220.0H 35.74% idle: 
cpu0
    61 root        1 -16 -135     0K     8K pgzero 0 679:47 27.83% pagezero
35199 www         1 122    0 71132K 42140K CPU1   1   0:35 26.56% httpd
35541 www         1  96    0 51452K 22452K select 0   0:21 15.14% httpd
    11 root        1 171   52     0K     8K RUN    1 192.5H 14.94% idle: 
cpu1
35391 www         1  20    0 63368K 34272K lockf  0   1:02  3.56% httpd
35467 www         1  97    0 50772K 20768K select 0   0:23  2.05% httpd
35447 www         1  98    0 51724K 22956K select 0   0:04  1.76% httpd
35390 www         1  20    0 51140K 22708K lockf  0   0:27  1.37% httpd
    44 root        1 -44 -163     0K     8K WAIT   1 161:04  1.27% swi1: net

This is:
FreeBSD myserver.net 6.1-PRERELEASE FreeBSD 6.1-PRERELEASE #2: Sun Feb 
5 00:07:27 CET 2006

I have 'aj' linked as /etc/malloc.conf.

Any ideas on why this is so? 30% CPU just seems way too much for such thing.