Messages in this thread | | | From | Vincent Guittot <> | Date | Thu, 1 Feb 2018 08:57:45 +0100 | Subject | Re: [PATCH 5/8] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver |
| |
On 31 January 2018 at 16:27, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: > On 31/01/2018 10:56, Vincent Guittot wrote: >> On 31 January 2018 at 10:50, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: >>> On 31/01/2018 10:46, Vincent Guittot wrote: >>>> On 31 January 2018 at 10:33, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: >>>>> On 31/01/2018 10:01, Vincent Guittot wrote: >>>>>> Hi Daniel, >>>>>> >>>>>> On 23 January 2018 at 16:34, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: >>>>> >>>>> [ ... ] (please trim :) >>>>> >>>>>>> + /* >>>>>>> + * Each cooling device is per package. Each package >>>>>>> + * has a set of cpus where the physical number is >>>>>>> + * duplicate in the kernel namespace. We need a way to >>>>>>> + * address the waitq[] and tsk[] arrays with index >>>>>>> + * which are not Linux cpu numbered. >>>>>>> + * >>>>>>> + * One solution is to use the >>>>>>> + * topology_core_id(cpu). Other solution is to use the >>>>>>> + * modulo. >>>>>>> + * >>>>>>> + * eg. 2 x cluster - 4 cores. >>>>>>> + * >>>>>>> + * Physical numbering -> Linux numbering -> % nr_cpus >>>>>>> + * >>>>>>> + * Pkg0 - Cpu0 -> 0 -> 0 >>>>>>> + * Pkg0 - Cpu1 -> 1 -> 1 >>>>>>> + * Pkg0 - Cpu2 -> 2 -> 2 >>>>>>> + * Pkg0 - Cpu3 -> 3 -> 3 >>>>>>> + * >>>>>>> + * Pkg1 - Cpu0 -> 4 -> 0 >>>>>>> + * Pkg1 - Cpu1 -> 5 -> 1 >>>>>>> + * Pkg1 - Cpu2 -> 6 -> 2 >>>>>>> + * Pkg1 - Cpu3 -> 7 -> 3 >>>>>> >>>>>> >>>>>> I'm not sure that the assumption above for the CPU numbering is safe. >>>>>> Can't you use a per cpu structure to point to resources that are per >>>>>> cpu instead ? so you will not have to rely on CPU ordering >>>>> >>>>> Can you elaborate ? I don't get the part with the percpu structure. >>>> >>>> Something like: >>>> >>>> struct cpuidle_cooling_cpu { >>>> struct task_struct *tsk; >>>> wait_queue_head_t waitq; >>>> }; >>>> >>>> DECLARE_PER_CPU(struct cpuidle_cooling_cpu *, cpu_data); >>> >>> I got this part but I don't get how that fixes the ordering thing. >> >> Because you don't care of the CPU ordering to retrieve the data as >> they are stored per cpu directly > > That's what I did initially, but for consistency reasons with the > cpufreq cpu cooling device which is stored in a list and the combo cpu > cooling device, the cpuidle cooling device must be per cluster and > stored in a list.
I'm not sure to catch your problem. You can still have cpuidle cooling device per cluster and stored in the list but keep per cpu data in a
AFAICT, you will not have more than one cpu cooling device registered per CPU so one per cpu variable that will gathers cpu private data should be enough ?
> > Alternatively I can do: > > struct cpuidle_cooling_device { > struct thermal_cooling_device *cdev; > - struct task_struct **tsk; > + struct task_struct __percpu *tsk; > struct cpumask *cpumask; > struct list_head node; > struct hrtimer timer; > struct kref kref; > - wait_queue_head_t *waitq; > + wait_queue_head_t __percpu waitq; > atomic_t count; > unsigned int idle_cycle; > unsigned int state; > };
struct cpuidle_cooling_device { struct thermal_cooling_device *cdev; struct cpumask *cpumask; struct list_head node; struct hrtimer timer; struct kref kref; atomic_t count; unsigned int idle_cycle; unsigned int state; };
struct cpuidle_cooling_cpu { struct task_struct *tsk; wait_queue_head_t waitq; }; DECLARE_PER_CPU(struct cpuidle_cooling_cpu *, cpu_data);
You continue to have cpuidle_cooling_device allocated dynamically per cluster and added in the list but task and waitq are stored per cpu
> > > -- > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog >
| |