On 2013년 04월 02일 16:34, Daniel Lezcano wrote: > On 04/02/2013 08:17 AM, jonghwa3.lee@xxxxxxxxxxx wrote: >> On 2013년 04월 02일 14:00, Daniel Lezcano wrote: >> >>> On 04/01/2013 10:24 AM, Jonghwa Lee wrote: >>>> This patch adds idle state time stamp to cpuidle device structure to >>>> notify its current idle state. If last enter time is newer than last >>>> exit time, then it means that the core is in idle now. >>>> >>>> Signed-off-by: Jonghwa Lee <jonghwa3.lee@xxxxxxxxxxx> >>>> --- >>> >>> The patch description does not explain what problem you want to solve, >>> how to solve it and the patch itself shows nothing. >>> >>> Could you elaborate ? >> >> >> I'm sorry for lacking description. I supplement more. >> >> This patch does add time-stamp for idle enter/exit only nothing more. >> The reason why I needed them is that I wanted to know current cpu idle >> state. It is hard to know whether cpu is in idle or not now. > > Did you looked at: > > include/linux/sched.h:extern int idle_cpu(int cpu); > Yes, I did. > ? > >> When I check the cpuidle state usage, sometimes the information is wrong. >> Because it is updated only when the cpu exits the idle state. So while the >> cpu is idling, the cpuidle state usage holds past one. Therefore I put >> the time-stamp for cpuidle enter/exit for checking current idling and >> calculating idle state usage correctly. >> >> I just make this patch temporary for my cpufreq governor work. So, it just >> use time-stamp for all idle state together. After RFC working, I have a plan >> to update this patch to use timestamp for each idle state. > > I suggest you look at the enter_idle / exit_idle function and make your > governor to subscribe to the IDLE_START/EXIT notifiers. > > arch/x86/kernel/process.c > > These are defined for the x86 architecture, maybe worth to add it to > another architecture. > Thanks for your opinion. Actually, I work on ARM architecture and I knew that the attempt of applying idle notifier was failed. You probably knew it, because the link you gave me before is that attempt. (https://lkml.org/lkml/2012/2/7/504) :) Currently, there is only notifying call which is for led in arch/arm/kernel/process.c and I think it isn't for me to use. Anyway, Do you really think it is better way to use notifier than my way? Because I think it is too heavy for me. On my board, sometimes entering idle happened hundreds times during the 100ms. I don't want to call notifier that much time. IMO, just moving local variable to per-cpu variable for showing the enter/exit time looks better although it requires code modification on cpudile side. What do you think? Thanks, Jonghwa. > Thanks > -- Daniel > -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
