From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: 50 Watt idle power regression bisected to Linux-3.10 Date: Wed, 11 Dec 2013 17:44:42 +0100 Message-ID: <20131211164442.GC2480@laptop.programming.kicks-ass.net> References: <1386732093.5964.6.camel@marge.simpson.net> <20131211113839.GF21683@pd.tnic> <20131211115239.GA21999@twins.programming.kicks-ass.net> <1386764955.12005.60.camel@marge.simpson.net> <20131211124352.GB21999@twins.programming.kicks-ass.net> <20131211144238.GA4510@gmail.com> <20131211150911.GA11048@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20131211150911.GA11048@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar Cc: Thomas Gleixner , Mike Galbraith , Borislav Petkov , Len Brown , Linux PM list , "linux-kernel@vger.kernel.org" , Jeremy Eder , x86@kernel.org List-Id: linux-pm@vger.kernel.org On Wed, Dec 11, 2013 at 04:09:11PM +0100, Ingo Molnar wrote: > > * Thomas Gleixner wrote: > > > On Wed, 11 Dec 2013, Ingo Molnar wrote: > > > > > > Another thing that is required I think is to issue a write barrier > > > before CLFLUSH instruction. By my (possibly incorrect ...) reading of > > > the documentation CLFLUSH does not appear to be ordered (at all), so > > > it might execute before the modification to the affected memory? > > > > We already have a write barrier in the code which modifies > > current_thread_info()->flags. > > Which code is that, could you please cite it? (I tried finding it but > my grep-fu failed me.) current_set_polling_and_test().