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From Dragon <dra...@crimson-dragon.com>
Subject Re: [users@httpd] High load, low CPU and processes in state "devfs"
Date Fri, 13 Jun 2008 21:56:57 GMT
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.


Dragon

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Venimus, Saltavimus, Bibimus (et naribus canium capti sumus)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



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