Date: 01 Nov 1997 16:47:28 +0100 From: Wolfram Schneider <wosch@cs.tu-berlin.de> To: "Jordan K. Hubbard" <jkh@time.cdrom.com> Cc: smp@freebsd.org Subject: Re: Some SMP timing tests. Message-ID: <p1ira90ehv3.fsf@panke.panke.de> In-Reply-To: "Jordan K. Hubbard"'s message of Fri, 31 Oct 1997 19:55:52 -0800 References: <26870.878356552@time.cdrom.com>
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"Jordan K. Hubbard" <jkh@time.cdrom.com> writes:
> The most interesting thing about these numbers was that at "high job
> counts", where one would expect performance to start to actually
> degrade due to having too many compiles competing for various system
> resources, performance did not fall as expected. This leads me to
> believe that our make actually artificially limits the parallelism
> number to somewhere below 20. I haven't bothered to look into make's
> code more thoroughly in verifying this, but that's certainly what it
> looks like.
If you have a Makefile with 5 targets (e.g. 4 *.c files, 1 manpage),
make can only create 5 jobs at once. Not surprising ;-)
I guess the average Makefile has 3 targets.
-j max_jobs
Specify the maximum number of jobs that make may have running at
^^^^^^^^^^^^^^ ^^^
any one time.
--
Wolfram Schneider <wosch@apfel.de> http://www.apfel.de/~wosch/
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