Re: Re: Perl and mutli processors

well it's a linear script, but I'm into rewriting it to fork childs to handle some tasks.Will this help on a dual cpu system?
Otherwise, my question might have been : how much more powerfull is a dual CPU server under linux (cause we're having an argument about it in my company).
In my opinion, having 2 cpu will mean that processes like apache/mysql et al will balance the load beetween the cpus so my script will automatically get more CPU time, even if it's not specifically written to take the advantage of 2 processors. Am I correct ?

Comment on Re: Re: Perl and mutli processors

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Re: Re: Re: Perl and mutli processors by grantm (Parson) on Oct 14, 2002 at 09:29 UTC
Yes, two processors can run two programs simultaneously even if each process is single threaded. Of course if your script is 'IO bound' (most of it's time is spent waiting for data from disk or network) then extra CPUs aren't going to do much for it. Without knowing what your script is doing, I can't say what benefit you might getting from forking children. Of course if you fork too many you'll use up available physical memory and once your system starts to swap, the performance will get worse. Discussions/arguments are probably not going to help you too much. You need to do some profiling to work out what your script is spending its time doing (same goes for your system in general) before you can make any sensible decisions about steps to improve performance.	[reply]

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Re: Re: Re: Perl and mutli processors
by grantm (Parson) on Oct 14, 2002 at 09:29 UTC

Yes, two processors can run two programs simultaneously even if each process is single threaded.

Of course if your script is 'IO bound' (most of it's time is spent waiting for data from disk or network) then extra CPUs aren't going to do much for it.

Without knowing what your script is doing, I can't say what benefit you might getting from forking children. Of course if you fork too many you'll use up available physical memory and once your system starts to swap, the performance will get worse.

Discussions/arguments are probably not going to help you too much. You need to do some profiling to work out what your script is spending its time doing (same goes for your system in general) before you can make any sensible decisions about steps to improve performance.

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