Re: high %system time

Bill Moran wrote:
> On Tue, 06 Jun 2006 09:19:10 -0400
> Jacob Coby <jcoby@listingbook.com> wrote:
>
>> We recently upgraded from php 4.3.10 to 5.1.2, and the %system time has
>> skyrocketed:
>>
>> Cpu(s): 42.8% us, 43.6% sy,  0.0% ni, 11.3% id,  2.2% wa,  0.2% hi,  0.0% si
>> Mem:   8312844k total,  7566168k used,   746676k free,    22356k buffers
>> Swap:  2040244k total,      520k used,  2039724k free,  6920384k cached
>>
>> it used to be around 5% to 10%.  The server is a quad-xeon dell pe 6650
>> running CentOS 4.2 with 8G of RAM running pg 8.1.1.
>>
>> How can I determine what is causing such high system load?  it seems to
>> have immediately jumped with the php upgrade.
>
> This sounds more like a PHP question than a PostgreSQL question.

I know.  I'm looking for advice on what would affect system time.  Its
actually not related so much to the php upgrade as a major code change
we did.  What baffles me is that the db abstraction layer didn't change.

>
> However, we had a similar problem recently, and I ran ktrace (on FreeBSD)
> to track down the system calls.  2 things jumped out:
> 1) pg_connect() creates a LOT of system time compared to pg_pconnect()

We use pg_pconnect().  We also reuse connections to avoid the overhead
of RESET ALL (php issues a RESET ALL on persistent connections, which
can take up to 0.1s)

> 2) require_once() and include_once() are truly evil.

Can you elaborate a bit on this?  Privately if you want since it's off
topic for this list.

Thanks.
--
Jacob Coby