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From Josh Chamas <j...@chamas.com>
Subject Re: [mp2] Benchmarks comparing mp2 vs. mp1
Date Wed, 07 May 2003 02:17:51 GMT
Stas Bekman wrote:
> Josh Chamas wrote:
> 
>> Stas Bekman wrote:
>>
>>>
>>> If you know of such a problem, either solve it or use the preforked 
>>> MPM if you can. Using worker mpm with only one perl interpreter per 
>>> thread, will be definitely slower than using a prefork mpm. Of course 
>>> platforms like winFU have no choice but using their winnt mpm.
>>>
>>
>> What would be slower about this?  Let's say in the given config with
>> 20 max clients, 5 processes, 4 threads each, and 1 perl interp each,
>> should not 4 CPUs be able to run concurrently on such a benchmark?
>> How would increasing the number of perl interpreters hurt this,
>> are there some serializing issues that are particularly bad with
>> mp2 and worker mpm ?  Is it just the threaded per penalty that makes
>> this slower ( apparently threaded perl has a general 10-20% 
>> performance hit
>> from other benchmarks I've seen ).
> 
> 
> Yes, enabling threads in perl and compiling mod_perl with it makes 
> mod_perl slower if you don't use the benefit of the threaded 
> environment, which is the case if you use only one perl interpreter per 
> process. You both use more memory because more information needs to be 


Thanks for the clarification.  I believe there can be an advantage to
having the one perl intepreter per process model in worker mpm mode,
that being namely to increase MaxClients capacity, which is a bane
on standard mod_perl 1.x setups, such that we need to go to dual httpd
or proxy/mod_perl httpd setups.  So, at this cost of some speed / CPU hit,
doesn't a setup of 1 perl interpreter per process with many threads
make sense if the bottleneck is the MaxClients / memory capacity,
where a web site is being servied with non-mod_perl type requests
that can be made concurrent to the mod_perl interpreter doing its thing?
This would be to solve the "many users / slow modem" problem we often
talk about with mp1.

I was actually thinking about upgrading to such a config, to increase
that MaxClients capacity, but not worrying so much about perl CPAN module,
and c lib threading issues, yet take advantage of the threaded model
for things like static images...

Am I crazy to think this way? :)

Thanks,

Josh

________________________________________________________________
Josh Chamas, Founder                   phone:925-552-0128
Chamas Enterprises Inc.                http://www.chamas.com
NodeWorks Link Checking                http://www.nodeworks.com


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