Re: High load, low CPU and processes in state "devfs" (Apache Users)

On 6/13/08, Stut <stuttle@xxxxxxxxx> wrote:

On 13 Jun 2008, at 22:56, Dragon wrote:

Stut wrote:

On 13 Jun 2008, at 22:37, Dragon wrote:

Stut wrote:

Hi,

I have a problem with one of the web servers I manage. It runs
FreeBSD
6.2, Apache 2.2.8 and PHP 5.2.1. It runs a high-ish number of pre- fork
processes (usually around 240).

What basically happens is that during our peak hours in the evening
the site becomes very slow as does everything on the server. The top
output shows nearly all httpd processes in the state "devfs" and the
load is jumping up over 10 but the CPU is 70% idle. There's plenty of
free memory, over 4GB, and lots of available disk space.

While it's in this state all disk access is painfully slow. I've
checked all the drives and the RAID card status and everything
appears
to be fine. It also recovers itself after a few hours when the
traffic
dies down again.

I've spent a lot of today Googling but can't find any reference to
this particular combination of symptoms. Does anyone have any ideas?

---------------- End original message. ---------------------

It sounds to me like your system is waiting on disk resources (I am
assuming that is what the devfs state is), it is very likely trying
to use swap space.

Now much memory does this system have?

If it has insufficient memory to keep most things in RAM, it is
going to use a lot of swap and that will slow things down
considerably.

Oh how I wish it were that simple...

Mem: 1629M Active, 770M Inact, 392M Wired, 68K Cache, 214M Buf, 4791M
Free
Swap: 8192M Total, 8192M Free

No swap in use, plenty of free memory.
---------------- End original message. ---------------------

Well, I took my best shot on the info presented. I still think there is something in the disk I/O path that is acting as a bottleneck.

Sorry it isn't so easy, I have nothing else here. Wish I could help.

No worries, thanks for trying.

I agree that it's probably disk-related, but other than these symptoms I can't find anything wrong.

I'll see if the FreeBSD list can help.

-Stut

--
http://stut.net/

---------------------------------------------------------------------
The official User-To-User support forum of the Apache HTTP Server Project.
See <URL:http://httpd.apache.org/userslist.html> for more info.
To unsubscribe, e-mail: users-unsubscribe@xxxxxxxxxxxxxxxx
" from the digest: users-digest-unsubscribe@xxxxxxxxxxxxxxxx
For additional commands, e-mail: users-help@xxxxxxxxxxxxxxxx