From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [GIT PULL] First batch of KVM changes for 4.1 Date: Fri, 17 Apr 2015 12:36:54 +0200 Message-ID: <20150417103654.GE5029@twins.programming.kicks-ass.net> References: <1428678089-16291-1-git-send-email-pbonzini@redhat.com> <20150417085238.GJ17717@twins.programming.kicks-ass.net> <20150417091745.GA24151@twins.programming.kicks-ass.net> <5530DBED.5080508@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, gleb@kernel.org, kvm@vger.kernel.org, Ralf Baechle , mtosatti@redhat.com, luto@kernel.org To: Paolo Bonzini Return-path: Content-Disposition: inline In-Reply-To: <5530DBED.5080508@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Fri, Apr 17, 2015 at 12:09:49PM +0200, Paolo Bonzini wrote: > > > On 17/04/2015 11:17, Peter Zijlstra wrote: > > On Fri, Apr 17, 2015 at 10:52:38AM +0200, Peter Zijlstra wrote: > >> On Fri, Apr 10, 2015 at 05:01:29PM +0200, Paolo Bonzini wrote: > >>> include/linux/sched.h | 8 + > >>> kernel/sched/core.c | 15 + > >> > >> Can you please not puke over the scheduler without Acks from at least > >> one maintainer? > > Sorry, this was done while I was not handling the KVM tree. At the very > least the commit message should have included the original hashes of the > commit and the revert. This way one could have found the original Acks: > > commit 582b336ec2c0f0076f5650a029fcc9abd4a906f7 > Author: Marcelo Tosatti > Date: Tue Nov 27 23:28:54 2012 -0200 > > sched: add notifier for cross-cpu migrations > > Originally from Jeremy Fitzhardinge. > > Acked-by: Ingo Molnar > Signed-off-by: Marcelo Tosatti Still not a good reason to sneak it back it now, after I got it taken out. There was a reason it was removed, prior acks (esp. 2 year old ones) do not count one whit _NOW_. Also, Ingo later agreed that is was a mistake, http://marc.info/?l=linux-kernel&m=137346715521978&w=2 which is an effective retract of whatever ACK that was. It was crap code then and its crap code now. > >> I complained about this very thing two years ago: > >> > >> http://marc.info/?l=linux-kernel&m=137345253916751 > >> > >> And now it magically re-appears WTF! > > > > And I really don't understand _why_ you need that extra callback in the > > first place. You already have preempt notifiers, just track if you came > > in on another cpu than you went out on and voila! > > Then you pay for _all_ preemptions of _all_ processes in the guest, > instead of the hopefully rare ones that do a CPU migration. Now you make everybody pay for your crap, x86-64 paravirt or not. Keep the cost by those who need it. Please take it out, ASAP.