From: Ken Moffat <zarniwhoop@ntlworld.com>
To: Jeff Epler <jepler@unpythonic.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: make -jN (n>1) ineffective in 4.2.0-rc on AMD Phenom
Date: Wed, 15 Jul 2015 13:28:00 +0100 [thread overview]
Message-ID: <20150715122800.GA14373@milliways> (raw)
In-Reply-To: <20150715022331.GE70510@unpythonic.net>
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!
prev parent reply other threads:[~2015-07-15 12:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-14 23:39 make -jN (n>1) ineffective in 4.2.0-rc on AMD Phenom Ken Moffat
2015-07-15 0:13 ` Ken Moffat
2015-07-15 2:23 ` Jeff Epler
2015-07-15 12:28 ` Ken Moffat [this message]
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