Subject: Re: MP Perfomance
To: Zafer Aydogan <>
From: Simon Burge <>
List: tech-smp
Date: 03/19/2004 19:50:43
"Zafer Aydogan" wrote:

> after building successfully an MP Kernel, I wonder why the performance does
> not increase equally.
> Services like FTP runs slower compared to an UP Kernel on the same machine.

There is more kernel overhead in an MP kernel as more things need to be
locked, etc.  For a single non-threaded program, you probably will get
better performance from a UP kernel.

> Also compiling is not really faster. All I can detect is, that the avg load
> is the half since it shares on 2 processors.

Did you try "make -j N" for some value of N > 1?  I use N = 2*ncpus
here - that seems to be about the sweet spot.

> How can I detect, that 2 processors are running well? 

Try "top", and look for multiple lines with "CPU/n" in the STATE column.

> Where is the advantage of running multi?

In general, it's faster :)

Simon Burge                            <>
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