From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752623AbbGOM2N (ORCPT ); Wed, 15 Jul 2015 08:28:13 -0400 Received: from know-smtprelay-omc-7.server.virginmedia.net ([80.0.253.71]:37530 "EHLO know-smtprelay-omc-7.server.virginmedia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751638AbbGOM2M (ORCPT ); Wed, 15 Jul 2015 08:28:12 -0400 X-Originating-IP: [81.106.150.188] X-Spam: 0 X-Authority: v=2.1 cv=JuUM15MC c=1 sm=1 tr=0 a=DGj713NdaxKrsjjgQne7PA==:117 a=DGj713NdaxKrsjjgQne7PA==:17 a=NLZqzBF-AAAA:8 a=yEdEr6MRgwAA:10 a=IkcTkHD0fZMA:10 a=zOBTXjUuO1YA:10 a=mDV3o1hIAAAA:8 a=G4a8qauF08vUPjomiSQA:9 a=QEXdDO2ut3YA:10 Date: Wed, 15 Jul 2015 13:28:00 +0100 From: Ken Moffat To: Jeff Epler Cc: linux-kernel@vger.kernel.org Subject: Re: make -jN (n>1) ineffective in 4.2.0-rc on AMD Phenom Message-ID: <20150715122800.GA14373@milliways> References: <20150714233920.GA15565@milliways> <20150715022331.GE70510@unpythonic.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Clacks-Overhead: GNU Terry Pratchett Content-Transfer-Encoding: 8bit In-Reply-To: <20150715022331.GE70510@unpythonic.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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!