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Wysocki" , Alexander Gordeev , Anna-Maria Behnsen , Ben Segall , Boqun Feng , Christian Borntraeger , Dietmar Eggemann , Heiko Carstens , Ingo Molnar , Jan Kiszka , Joel Fernandes , Juri Lelli , Kieran Bingham , Madhavan Srinivasan , Mel Gorman , Michael Ellerman , Neeraj Upadhyay , Nicholas Piggin , "Paul E . McKenney" , Steven Rostedt , Sven Schnelle , Thomas Gleixner , Uladzislau Rezki , Valentin Schneider , Vasily Gorbik , Vincent Guittot , Viresh Kumar , Xin Zhao , linux-pm@vger.kernel.org, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 06/15] tick/sched: Unify idle cputime accounting Message-ID: References: <20260116145208.87445-1-frederic@kernel.org> <20260116145208.87445-7-frederic@kernel.org> <20260119142607.GG830229@noisy.programming.kicks-ass.net> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260119142607.GG830229@noisy.programming.kicks-ass.net> Le Mon, Jan 19, 2026 at 03:26:07PM +0100, Peter Zijlstra a écrit : > On Fri, Jan 16, 2026 at 03:51:59PM +0100, Frederic Weisbecker wrote: > > > +#ifdef CONFIG_NO_HZ_COMMON > > +void kcpustat_dyntick_start(void) > > +{ > > + if (!vtime_generic_enabled_this_cpu()) { > > + vtime_dyntick_start(); > > + __this_cpu_write(kernel_cpustat.idle_dyntick, 1); > > + } > > +} > > Why don't we need to make sure steal time is up-to-date at this point? Yes, there could be steal time since the last tick. It will be included and accounted in kcpustat_dyntick_stop() and not substracted from system or idle cputime (but it should!). This wrong behaviour is the same as the current upstream behaviour. So no known regression. But check the last patch of the series that tries to fix that: sched/cputime: Handle dyntick-idle steal time correctly Thanks. -- Frederic Weisbecker SUSE Labs