From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v5] cpuidle: menu: Handle stopped tick more aggressively Date: Mon, 20 Aug 2018 13:04:10 +0200 Message-ID: <20180820110410.GY2494@hirez.programming.kicks-ass.net> References: <1951009.1jlQfyrxio@aspire.rjw.lan> <1754612.IcCR94pSYR@aspire.rjw.lan> <1582055.9b67urWYFa@aspire.rjw.lan> <1572343.jWaXB8XNF1@aspire.rjw.lan> <20180814154441.GA13920@leoy-ThinkPad-X240s> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180814154441.GA13920@leoy-ThinkPad-X240s> Sender: linux-kernel-owner@vger.kernel.org To: leo.yan@linaro.org Cc: "Rafael J. Wysocki" , Linux PM , LKML , Frederic Weisbecker List-Id: linux-pm@vger.kernel.org On Tue, Aug 14, 2018 at 11:44:41PM +0800, leo.yan@linaro.org wrote: > I agree this patch can resolve the issue you mentioned in the commit > log, but this patch will be fragile for below case, so it will select > state1 but not state2, how about you think for this case? > > Idle_state0:: > target_residency TICK_USEC Prediction > | | / > V V / > -----------------------------------------------------> Time length > ^ ^ > | | > Idle_state1: Idle_state2: > target_residency target_residency If someone can demonstate this is an actual problem; then we need to fix it I suppose. But it would be very good to have a real world need/reproducer for it first.