[ic] Time for new hardware?

[Mike Heins]

Quoting Grant (emailgrant at gmail.com):
> >>>>>> I've been making a lot of optimizations lately and I think I'm to the
> >>>>>> point where my 4 cores just aren't able to keep up with demand during
> >>>>>> peak traffic hours each day.  Pages load quickly when I see fewer than
> >>>>>> 4 busy interchange processes in top but things slow down drastically
> >>>>>> after that.  Once I'm OK with the degree of optimization my ITL pages
> >>>>>> have undergone and I'm not IO-bound or memory-bound, is it time to
> >>>>>> throw CPU at the problem?
> >>>>>>
> >>>>>> I'm a little puzzled because I've seen my server perform much better
> >>>>>> under much greater loads in the past.  I thought my growing mysql
> >>>>>> tables could be the problem so I set up indexes and it has helped but
> >>>>>> my server still struggles under loads it used to handle without issue.
> >>>>>> I did notice that my tables are split about 50/50 between InnoDB and
> >>>>>> MyISAM and I'd like to make all of them InnoDB.
> >>>>>>
> >>>>>> - Grant
> >>>>>
> >>>>> Yeah, I would recommend to switch all them to InnoDB for consistency
> >>>>> and real transactions.
> >>>>>
> >>>>> You probably can find sufficient resources on MySQL optimization with
> >>>>> InnoDB if that is your bottleneck.
> >>>>
> >>>>
> >>>> Actually IO doesn't seem to be a bottleneck at this point.  It seems
> >>>> to be CPU as things slow down once I have 4 busy interchange processes
> >>>> on my quad-core CPU and iotop does not show much activity at that
> >>>> point.  Besides ITL optimization, is this a clear case of needing a
> >>>> faster CPU and more cores or is there anything else to consider first?
> >>>>
> >>>>
> >>>>> May I ask which webserver you are using?
> >>>>
> >>>>
> >>>> I'm using nginx reverse proxied to apache2.
> >>>
> >>> Did you consider to get rid of Apache?
> >>
> >>
> >> I'm certainly planning to do that but if I watch top it looks like my
> >> apache2 processes *barely* get above idle even when the web server is
> >> under heavy load.  The interchange processes get hammered.
> >>
> >
> > Which mode/settings do you use for the Interchange server? How
> > do you connect Nginx and Interchange?
> 
> 
> Here are my active traffic settings from interchange.cfg:
> 
> PreFork                 Yes
> StartServers            12
> MaxServers              0
> MaxRequestsPerChild     100
> HouseKeeping            2
> PIDcheck                3600
> ChildLife               3600
> 
> apache2 listens on a particular port and nginx sends page requests to
> apache2 over that port via the proxy_pass directive.  apache2 then
> hands off to interchange via Interchange::Link.

Apache is almost certainly not your problem.

CPU usage is not always Interchange -- your database uses CPU.

My top suspect is SQL queries that are not optimized. In my experience,
adding a few indices to help key queries usually solves this type of
problem.

-- 
Mike Heins
End Point -- Expert Internet Consulting    http://www.endpoint.com/
phone +1.765.253.4194  <mikeh at endpoint.com>

Fast, reliable, cheap.  Pick two and we'll talk.
-- unknown