Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1184208 > unrolled thread

Re: make -jN (n>1) ineffective in 4.2.0-rc on AMD Phenom

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: make -jN (n>1) ineffective in 4.2.0-rc on AMD Phenom Jeff Epler <jepler@unpythonic.net> - 2015-07-15 04:30 +0200
    Re: make -jN (n>1) ineffective in 4.2.0-rc on AMD Phenom Ken Moffat <zarniwhoop@ntlworld.com> - 2015-07-15 14:30 +0200

#1184208 — Re: make -jN (n>1) ineffective in 4.2.0-rc on AMD Phenom

GNU Make 4.1 has a problem that causes it to be unable to use the
desired level of parallelism.  Two people have reported that reverting a
commit which changes from fork to vfork "fixes" it. (i'm one of them,
unfortunately posting as anonymous in the tracker).

Hoewver, if you are also seeing the linux kernel version as relevant to
producing the problem, that's quite interesting, and the underlying
cause may be different.  We reproduced the problem on a range of older
kernels, from 3.2 to 3.18.

http://savannah.gnu.org/bugs/?44555

Jeff
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [next] | [standalone]

#1184757

On Tue, Jul 14, 2015 at 09:23:31PM -0500, Jeff Epler wrote:
> GNU Make 4.1 has a problem that causes it to be unable to use the
> desired level of parallelism.  Two people have reported that reverting a
> commit which changes from fork to vfork "fixes" it. (i'm one of them,
> unfortunately posting as anonymous in the tracker).
> 
> Hoewver, if you are also seeing the linux kernel version as relevant to
> producing the problem, that's quite interesting, and the underlying
> cause may be different.  We reproduced the problem on a range of older
> kernels, from 3.2 to 3.18.
> 
> http://savannah.gnu.org/bugs/?44555
> 
> Jeff

Thanks, but I think this is a different problem, I was probably not
clear : I specify make -j4 and make does indeed run 4 jobs, but it
is only getting the equivalent of 1 CPU instead of 4.  It is
running 4 jobs, but on the equivalent of 1  processor (so this takes
much longer than -j1).

The reason I think it is a different problem is that I upgraded to
make-4.1 in November and everything has been fine until now.

With 'top' from procps-ng-3.3.10 the display can show how active
each CPU is (indeed, I think that is the default) - on earlier
versions of 'top' I think that the output was very different.

ĸen
-- 
This one goes up to eleven!
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web