-DNOPROFILE with make buildworld...
Harrison Peter CSA BIRKENHEAD
peter.harrison at dwp.gsi.gov.uk
Wed Jun 22 08:32:27 GMT 2005
> -----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.
> R.F.Smith (http://www.xs4all.nl/~rsmith/) Please send e-mail
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