Re: tux on 2.4.27 kernel and referrer checking

[William Lovaton <williama_lovaton@coomeva.com.co>]

El jue, 28-10-2004 a las 18:55, Marek Habersack escribió:
> > Agree, but the new process scheduler is a lot smarter and it does a
> > really good job.
> Indeed

Yeah, it detects if a proccess is CPU bound or I/O bound and do the
appropriate management.


> > Mmmm... load avg of 300, 800... that's insane.  You just need a bigger
> > CPU this is just a matter of MHz.  With such a load you can't even type
> > on a terminal.
> Definitely so :>, but throwing in hardware is not a cure for bad software
> (kernel not being the bad one here). That way you're only avoiding finding
> the real reason of the load.

Mmmm... Are you using Apache/PHP?? Here are 2 advices:

1. Use Apache2 (In prefork mode) with PHP, it is faster than Apache 1.3.

2. You could use a custom format log in the apache web server.  At the
end you can put a filed (%T).  That will show you the total execution
time of a request (in seconds).  Then you can filter them for php
programas based on the extention and then you can get some statistics
and find out what programs are being slow.

I have a script that proccesses the modified log_file and, for example:
92% of the request takes 0 secs (< 1)
 6% takes 1 sec (>0 and <2)
 1% takes 2 sec (>2 and <3)

So, in my case more than 99% of the requests takes less that 3 secs. 
This is a higly interactive web app.  Our users are giving services to
customers "in real time" so responses times are very, very important.

Once you can get statistical data you can take decisions about what to
optimize first.


> > And 800 processes?? How much RAM do you have? what are the technical
> > specs of the server?
> P3/800 w 512 of RAM, for instance. And, trust me, with correctly written
> software such machine can do a LOT.

How many requests does it get per day?? per second?


> > BTW, if you upgrade the CPU you will need less RAM.
> as in that processes will execute their stuff faster and return the memory
> to the system? I don't think the two things are related in that way, if
> processes are executed faster, there will be more of them running in a unit
> of time, that's it. The memory usage will either remain the same in effect
> or increase.

No, according to your configuration in httpd.conf
[Max|Min]SpareServers.  You will need less httpd proccesses to handle
the load and then less RAM usage.

With extra CPU a proccess will end the request faster and the chances
that a new request finds an available proccess increase without the need
to fork extra proccesses.


> Do you always run stock vendor kernels? (just out of curiosity)

Yes, usually.  Although in my workstation I have 2.4.28-pre4 from
kernel.org


-William