From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753254AbdGSIDI (ORCPT ); Wed, 19 Jul 2017 04:03:08 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47558 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752109AbdGSIDD (ORCPT ); Wed, 19 Jul 2017 04:03:03 -0400 Date: Wed, 19 Jul 2017 10:02:57 +0200 From: Greg KH To: Ben Guthro Cc: Ingo Molnar , Peter Zijlstra , Linux Kernel Mailing List , Linus Torvalds , Mike Galbraith , Thomas Gleixner Subject: Re: Potential scheduler regression Message-ID: <20170719080257.GA10514@kroah.com> References: <20170705164850.lnziwloc6mko3mxo@hirez.programming.kicks-ass.net> <20170710092532.kzwgukzishwpzoq6@hirez.programming.kicks-ass.net> <20170710152629.GB13980@kroah.com> <20170711083014.jpdpcbo6rlh5uuti@gmail.com> <20170711095512.GA15168@kroah.com> <20170714065407.GA17327@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170714065407.GA17327@kroah.com> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 14, 2017 at 08:54:07AM +0200, Greg KH wrote: > On Thu, Jul 13, 2017 at 03:24:02PM -0400, Ben Guthro wrote: > > On Tue, Jul 11, 2017 at 5:55 AM, Greg KH wrote: > > > On Tue, Jul 11, 2017 at 10:30:14AM +0200, Ingo Molnar wrote: > > >> > > >> * Ben Guthro wrote: > > >> > > >> > > If people have experience with these in the "enterprise" distros, or any other > > >> > > tree, and want to provide me with backported, and tested, patches, I'll be > > >> > > glad to consider them for stable kernels. > > >> > > > > >> > > thanks, > > >> > > > > >> > > greg k-h > > >> > > > >> > I tried to do a simple cherry-pick of the suggested patches - but they > > >> > apply against files that don't exist in the 4.9 series. > > >> > > >> I think there are only two strategies to maintain a backport which work in the > > >> long run: > > >> > > >> - insist on the simplest fixes and pure cherry-picks > > >> > > >> - or pick up _everything_ to sync up the two versions. > > >> > > >> The latter would mean a lot of commits - and I'm afraid it would also involve the > > >> scheduler header split-up, which literally involves hundreds of files plus > > >> perpetual build-breakage risk, so it's a no-no. > > >> > > >> > In my release of 4.9 - I'm planning on doing the simpler revert of 1b568f0aab > > >> > that introduced the performance degradation, rather than pulling in lots of code > > >> > from newer kernels. > > >> > > >> That sounds much saner - I'd even Ack that approach for -stable as a special > > >> exception, than to complicate things with excessive backports. > > > > > > Ok, I'll revert that for the next stable release after this one that is > > > currently under review. > > > > > > thanks, > > > > > > greg k-h > > > > Greg, > > > > Just for clarity - is the "next one" 4.9.38 (posted today for review) > > - or the one following? > > Doh, I forgot it for this release, sorry about that, will try to get to > it for the next one after this. Now reverted. thanks, greg k-h