From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751410AbdFZFim (ORCPT ); Mon, 26 Jun 2017 01:38:42 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33725 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751335AbdFZFi1 (ORCPT ); Mon, 26 Jun 2017 01:38:27 -0400 From: Nicholas Piggin To: "Rafael J . Wysocki" Cc: Nicholas Piggin , linux-pm@vger.kernel.org, Vaidyanathan Srinivasan , "Gautham R . Shenoy" , Daniel Lezcano , linux-kernel@vger.kernel.org Subject: [PATCH] cpuidle: menu: allow state 0 to be disabled Date: Mon, 26 Jun 2017 15:38:15 +1000 Message-Id: <20170626053815.11845-1-npiggin@gmail.com> X-Mailer: git-send-email 2.11.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The menu driver does not allow state0 to be disabled completely. If it is disabled but other enabled states don't meet latency requirements, it is still used. Fix this by starting with the first enabled idle state. Fall back to state 0 if no idle states are enabled (arguably this should be -EINVAL if it is attempted, but this is the minimal fix). Acked-by: Gautham R. Shenoy Signed-off-by: Nicholas Piggin --- Hi Rafael, This patch is helpful when measuring power draw of polling, latency cost of idle states, etc. Please consider merging if you agree. Thanks, Nick drivers/cpuidle/governors/menu.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index b2330fd69e34..61b64c2b2cb8 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -286,6 +286,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) struct device *device = get_cpu_device(dev->cpu); int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); int i; + int first_idx; + int idx; unsigned int interactivity_req; unsigned int expected_interval; unsigned long nr_iowaiters, cpu_load; @@ -335,11 +337,11 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) if (data->next_timer_us > polling_threshold && latency_req > s->exit_latency && !s->disabled && !dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable) - data->last_state_idx = CPUIDLE_DRIVER_STATE_START; + first_idx = CPUIDLE_DRIVER_STATE_START; else - data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1; + first_idx = CPUIDLE_DRIVER_STATE_START - 1; } else { - data->last_state_idx = CPUIDLE_DRIVER_STATE_START; + first_idx = 0; } /* @@ -359,20 +361,28 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) * Find the idle state with the lowest power while satisfying * our constraints. */ - for (i = data->last_state_idx + 1; i < drv->state_count; i++) { + idx = -1; + for (i = first_idx; i < drv->state_count; i++) { struct cpuidle_state *s = &drv->states[i]; struct cpuidle_state_usage *su = &dev->states_usage[i]; if (s->disabled || su->disable) continue; + if (idx == -1) + idx = i; /* first enabled state */ if (s->target_residency > data->predicted_us) break; if (s->exit_latency > latency_req) break; - data->last_state_idx = i; + idx = i; } + if (idx == -1) + idx = 0; /* No states enabled. Must use 0. */ + + data->last_state_idx = idx; + return data->last_state_idx; } -- 2.11.0