Performance trouble on AMD64 webserver

[Sławek Żak]

Hi,

I've an 2 processor Opteron server (Sun v20z) with 4GB of RAM. It runs
FreeBSD 5.4-PRERELEASE. Everything is roses for 1-2 minutes after
starting Apache. Then the server freezes for 10-20 seconds then
resumes normal operation and chokes every couple of minutes. I tried
with 512 and 1024 httpd processes running. It is a fairly dynamic
webpage. Apache is coupled with mod_php. Each process takes 18-19MB of
resident memory.

I was tuning the machine after getting the nefarious "collectng PV
entries ..." message. I tried to increase PMAP_SHPGPERPROC and all. It
doesn't make the performance better.

Snapshot of vmstat -z gives:
...
PV ENTRY:         48,  4312872, 1611440, 616384,  8657151

The free value decreases to something close to 0 then the machine
chokes to get back up to some large value.

My loader.conf:

accf_data_load="YES"
accf_http_load="YES"

kern.ipc.nmbclusters="131072"
kern.maxusers="1024"

The sysctl.conf:

kern.ipc.somaxconn=1024

The customized part of kernel config:

options         VM_BCACHE_SIZE_MAX="(500*1024*1024)"
options         MAXDSIZ="(1000*1024*1024)"
options         MAXSSIZ="(1000*1024*1024)"
options         DFLDSIZ="(1000*1024*1024)"

options         PMAP_SHPGPERPROC=4096
options         PMAP_SHPGPERPROC=16384

options         SHMALL=131072
options         SHMMAXPGS=131072

I've also removed lots of SCSI hardware, Wifi and USB parts which I
don't need from the GENERIC config.

Any Ideas how to make it work?

Thanks, /S
--
Sławek Żak / UNIX Systems Administrator