-DNOPROFILE with make buildworld...

[Harrison Peter CSA BIRKENHEAD]

> -----Original Message-----
> From: Roland Smith [mailto:rsmith at xs4all.nl]
> Sent: 21 June 2005 19:07
> To: Harrison Peter CSA BIRKENHEAD
> Cc: freebsd-questions at freebsd.org
> Subject: Re: -DNOPROFILE with make buildworld...
> 
> 
> On Tue, Jun 21, 2005 at 01:49:06PM +0100, Harrison Peter CSA 
> BIRKENHEAD wrote:
> 
> > I've cvsup'ed my source tree, and stepping through the 
> instructions in
> > the handbook I note that it recommends running make buildworld with
> > -DNOPROFILE (or specifying it in make.conf). I'm not clear what the
> > impact of running profiled libraries is against non-profiled
> > libraries. I've done a quick search via google and through the list
> > archives without success.
> 
> It's not about profiled libraries, but profiling libraries. 
> Let me explain.
> 
> Programs that are compiled with profiling enabled gather data about
> their run-time behaviour, and write that to a file, usualy 
> gmon.out. If
> the program is linked to a profiling library, data about the 
> time spent
> running functions in that library are also recorded.
> 
> The contents of that file can be analyzed with the gprof 
> program, to see
> where the program spends its time.
> 
> Now if you compile a program with not-profiling libraries, 
> gprof cannot
> tell you much about the time your program spent in functions 
> in that library.


OK that makes sense now I think - it's basically an optimisation tool?
Thanks for the explanation. I don't imagine needing this at the moment
so noprofile looks like the correct option for me.


> 
> Programs that have been compiled with profiling enabled might run
> fractionally slower that without. But I doubt the difference is
> significant on a modern machine. 
> 
> I'll be bold and say that modern machines are so fast that there is
> seldom need to profile a program.


The machine in question is running on an Athlon XP 1800+ so it's not
that fast (or modern for that matter), but I take your point.


> 
> Roland
> -- 
> R.F.Smith (http://www.xs4all.nl/~rsmith/) Please send e-mail 
> as plain text.
> public key: http://www.xs4all.nl/~rsmith/pubkey.txt
> 

Thanks again,


Peter Harrison


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