[imp] Re: [horde] IMP & PHP Speed Improvements

[Mark Lucas]

Thanks for this. The spped increase is HUGE!!!

    Mark

Mark Lucas
Tel: (01323) 483259
Mob: (07788) 100757
Fax: (01323) 483305


Quoting Nate Mollring <nmollring@cennecs.org>:

> 
> http://www.php-accelerator.co.uk/  helped both my Horde installs.  Pages are
> 
> served quicker and server load is much less.  I have a 150+ users on the 
> production server.  From the site:
> 
> "Every time a PHP script is accessed, the PHP engine must open the script
> file 
> and read, parse, and compile the file contents into a compiled form. Only
> then 
> can the compiled code be executed. With scripts often including other
> scripts, 
> this work can become a significant part of the overall time to deliver a
> page. 
> It can also impact I/O performance, and require much dynamic memory
> allocation 
> that in itself can be time consuming. 
> 
> The reality, however, is that most PHP scripts never change from one access
> to 
> the next; indeed they may never change for weeks, months, or even years. The
> 
> Accelerator works to eliminate the penalty of processing scripts that never
> 
> change, and by caching the compiled scripts in shared memory, delivers 
> significant performance gains as a result. Note that this is very different
> to 
> caching script output. PHPA doesn't do this, scripts remain fully dynamic,
> and 
> if they do change then PHPA caches a new version - they just run faster! 
> 
> So by caching, the Accelerator eliminates:
> 
> 
> reading of source code 
> parsing of source code 
> compiled code generation 
> many memory allocation and copying operations 
> disk related operations 
> Once script execution has completed, compiled versions of any new or modified
> 
> scripts are immediately cached on disk for later reuse. This guarantees good
> 
> acceleration, but scripts are then cached in shared memory, and offering the
> 
> maximum performance gains. 
> The Accelerator has one other performance enhancing feature - a built-in code
> 
> optimiser. Although in it's early stages, the optimiser reduces the size of
> 
> compiled code and improves the code by removing unnecessary operations. 
> 
> So in summary, by aggressively removing operations causing performance 
> overhead, the Accelerator is able to deliver performance rivalling the very
> 
> best alternatives, and for free! "
> 
> Hope this helps, 
> Nate
> 
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