Re: [ng-spice-devel] A few questions


To ng-spice-devel@ieee.ing.uniroma1.it
From "Arno W. Peters" <a.w.peters@ieee.org>
Date Thu, 16 Nov 2000 21:25:43 +0100
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In-Reply-To <Pine.LNX.3.96.1001116141435.18465B-100000@ieee.ing.uniroma1.it >; from pnenzi@ieee.ing.uniroma1.it on Thu, Nov 16, 2000 at 02:23:02PM +0100
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On Thu, Nov 16, 2000 at 02:23:02PM +0100, Paolo Nenzi wrote:
> On Thu, 16 Nov 2000, Alan Gillespie wrote:
>
> > While I was compiling rework-13, I noticed that it took
> > 35 minutes on Linux (Mandrake 7.1). It only takes 7 minutes
> > for my own code in Win32 using the Watcom compiler, and 5
> > minutes with Borland. 
> 
> You are right, it takes a hell of time to compile, may be that gcc isn't
> a fast compiler.
> 
> > Is 35 minutes a reasonable time to
> > expect with Linux/gcc with that hardware ?
> 
> It is the same time (more or less) on a celeron 400
> 
> > However, the upside is that on one of my test simulations,
> > it seems to run 30% faster than even the Watcom compiler.
> > I know that the last time I compiled my own stuff on
> > Linux/gcc, it wasn't significantly different in performance
> > from the Win32 stuff, and it was Win32 which was faster.
> 
> May be that Arno have turned on some compiler optimization or that the
> gcc you are using is the 2.9.xx and not the 2.7.2

There are a number of things that affect compiler speed.  Here are a
number of hints to speed up the compilation process:

 compile only static libraries (i.e., ./configure --disable-shared)
 increase internal memory (the more the better)
 compile with make -j4 for 4 parallel compile processes
 turn off debugging symbols (i.e., no -g switch)
 turn off optimization (i.e., no -O switch)

Notably the generation of position independent code (PIC) is time
consuming.  I don't know if ngspice still compile if you only specify
you wish to build static programs.  I remember it giving problems at
link time.  Could somebody verify this?

Regards,
-- 
Arno

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