From: Abhishek Goel <huntbag@linux.vnet.ibm.com> To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-pm@vger.kernel.org Cc: rjw@rjwysocki.net, daniel.lezcano@linaro.org, mpe@ellerman.id.au, Abhishek Goel <huntbag@linux.vnet.ibm.com> Subject: [PATCH 1/2] cpuidle : auto-promotion for cpuidle states Date: Fri, 22 Mar 2019 01:25:29 -0500 [thread overview] Message-ID: <20190322062530.7586-2-huntbag@linux.vnet.ibm.com> (raw) In-Reply-To: <20190322062530.7586-1-huntbag@linux.vnet.ibm.com> Currently, the cpuidle governors (menu /ladder) determine what idle state an idling CPU should enter into based on heuristics that depend on the idle history on that CPU. Given that no predictive heuristic is perfect, there are cases where the governor predicts a shallow idle state, hoping that the CPU will be busy soon. However, if no new workload is scheduled on that CPU in the near future, the CPU will end up in the shallow state. In case of POWER, this is problematic, when the predicted state in the aforementioned scenario is a lite stop state, as such lite states will inhibit SMT folding, thereby depriving the other threads in the core from using the core resources. To address this, such lite states need to be autopromoted. The cpuidle- core can queue timer to correspond with the residency value of the next available state. Thus leading to auto-promotion to a deeper idle state as soon as possible. Signed-off-by: Abhishek Goel <huntbag@linux.vnet.ibm.com> --- drivers/cpuidle/cpuidle.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 2406e2655..c4d1c1b38 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -584,11 +584,8 @@ static void __cpuidle_unregister_device(struct cpuidle_device *dev) static void __cpuidle_device_init(struct cpuidle_device *dev) { - int i; memset(dev->states_usage, 0, sizeof(dev->states_usage)); dev->last_residency = 0; - for (i = 0; i < CPUIDLE_STATE_MAX; i++) - dev->states_usage[i].disable = true; } /** -- 2.17.1
WARNING: multiple messages have this Message-ID (diff)
From: Abhishek Goel <huntbag@linux.vnet.ibm.com> To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-pm@vger.kernel.org Cc: daniel.lezcano@linaro.org, rjw@rjwysocki.net, Abhishek Goel <huntbag@linux.vnet.ibm.com> Subject: [PATCH 1/2] cpuidle : auto-promotion for cpuidle states Date: Fri, 22 Mar 2019 01:25:29 -0500 [thread overview] Message-ID: <20190322062530.7586-2-huntbag@linux.vnet.ibm.com> (raw) In-Reply-To: <20190322062530.7586-1-huntbag@linux.vnet.ibm.com> Currently, the cpuidle governors (menu /ladder) determine what idle state an idling CPU should enter into based on heuristics that depend on the idle history on that CPU. Given that no predictive heuristic is perfect, there are cases where the governor predicts a shallow idle state, hoping that the CPU will be busy soon. However, if no new workload is scheduled on that CPU in the near future, the CPU will end up in the shallow state. In case of POWER, this is problematic, when the predicted state in the aforementioned scenario is a lite stop state, as such lite states will inhibit SMT folding, thereby depriving the other threads in the core from using the core resources. To address this, such lite states need to be autopromoted. The cpuidle- core can queue timer to correspond with the residency value of the next available state. Thus leading to auto-promotion to a deeper idle state as soon as possible. Signed-off-by: Abhishek Goel <huntbag@linux.vnet.ibm.com> --- drivers/cpuidle/cpuidle.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 2406e2655..c4d1c1b38 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -584,11 +584,8 @@ static void __cpuidle_unregister_device(struct cpuidle_device *dev) static void __cpuidle_device_init(struct cpuidle_device *dev) { - int i; memset(dev->states_usage, 0, sizeof(dev->states_usage)); dev->last_residency = 0; - for (i = 0; i < CPUIDLE_STATE_MAX; i++) - dev->states_usage[i].disable = true; } /** -- 2.17.1
next prev parent reply other threads:[~2019-03-22 6:26 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-22 6:25 [PATCH 0/2] Auto-promotion logic for cpuidle states Abhishek Goel 2019-03-22 6:25 ` Abhishek Goel 2019-03-22 6:25 ` Abhishek Goel [this message] 2019-03-22 6:25 ` [PATCH 1/2] cpuidle : auto-promotion " Abhishek Goel 2019-03-22 6:25 ` [PATCH 2/2] cpuidle : Add auto-promotion flag to cpuidle flags Abhishek Goel 2019-03-22 6:25 ` Abhishek Goel 2019-03-22 7:38 ` [PATCH 0/2] Auto-promotion logic for cpuidle states Abhishek 2019-03-22 7:38 ` Abhishek 2019-03-22 7:29 Abhishek Goel 2019-03-22 7:29 ` [PATCH 1/2] cpuidle : auto-promotion " Abhishek Goel 2019-03-22 7:29 ` Abhishek Goel 2019-03-22 9:45 ` Rafael J. Wysocki 2019-03-22 9:45 ` Rafael J. Wysocki 2019-03-22 13:26 ` Daniel Lezcano 2019-03-22 13:26 ` Daniel Lezcano 2019-04-01 5:11 ` Abhishek 2019-04-01 5:11 ` Abhishek 2019-04-04 10:21 ` Daniel Lezcano 2019-04-04 10:21 ` Daniel Lezcano 2019-04-04 10:54 ` Gautham R Shenoy 2019-04-04 10:54 ` Gautham R Shenoy 2019-04-04 11:10 ` Abhishek 2019-04-04 11:10 ` Abhishek
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