How busy is your site? Have you had a recent spike in traffic?

I would suggest looking at the response times from mysql. In particular,
turn on the slow query log and set the long query time to 1 second or even
less to see what comes up (you need at least mysql 5.1 to set it to
non-integer values). You can use a tool like "mk-query-digest" from maatkit
to summarize the slow log and get a sense of what may be holding up your php
processes.

You could also profile your php application using xdebug and view the
resulting files using a grind tool to determine where php is spending most
of its time. Profiling will most definitely crash your application,
especially since you're already seeing 100% CPU utilization but you can run
it for a short period of time and review the resulting grind files.

Its unlikely that this is an Nginx problem.



On Tue, Oct 26, 2010 at 7:07 AM, Phil Bayfield <phil@techlightenment.com>wrote:

> Your formulas look interesting, will give them a try next time I'm doing
> some optimising.
> Normally I would just make a rough guess based off req/sec, execution times
> etc and fine tune with ab.
>
>
> On 26 October 2010 11:58, SplitIce <mat999@gmail.com> wrote:
>
>> ive found that if you have no blocking functions in php, aka its CPU bound
>> then number of CPU cores+1 is the most efficient. If it has mysql (most
>> likely does) and other IO bound operations then *2 or *3 is fine. values
>> between 20-30 are common in decent scale web servers, in fact on my i7 8gb
>> ram I run 20, on my amd x2 4gb ram I run 15.
>>
>> On Tue, Oct 26, 2010 at 9:52 PM, Phil Bayfield <phil@techlightenment.com>wrote:
>>
>>> Sorry didn't read you config before posting, you already have this. :)
>>>
>>> You probably need to reduce the number of child processes, more is not
>>> better.
>>>
>>> On intensive PHP applications I've found lower is better.
>>>
>>> For example, if you have 100 concurrent connections, this doesn't mean
>>> you necessarily need 100 PHP-FPM children.
>>>
>>>>
>>>
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>>
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