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Message-id: <51D276E3.9030206@samsung.com> Date: Tue, 02 Jul 2013 15:44:51 +0900 From: Chanwoo Choi <cw00.choi@...sung.com> To: Viresh Kumar <viresh.kumar@...aro.org> Cc: rjw@...k.pl, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, cpufreq@...r.kernel.org, kyungmin.park@...sung.com, myungjoo.ham@...sung.com Subject: Re: [PATCH v4] cpufreq: stats: Add 'load_table' debugfs file to show accumulated data of CPUs On 06/28/2013 07:13 PM, Viresh Kumar wrote: > On 28 June 2013 14:52, Chanwoo Choi <cw00.choi@...sung.com> wrote: >> On 06/28/2013 05:18 PM, Viresh Kumar wrote: >>> On 28 June 2013 13:18, Chanwoo Choi <cw00.choi@...sung.com> wrote: > >>> Can you describe a bit about the layout this will create in debugfs? >>> I thought you will have a load_table file per policy->cpu ?? >>> >> >> The debugfs_cpufreq is debugfs root directory (/sys/kernel/debug/cpufreq) > > Which you are creating anyway in your patch. > >> and debugfs_cpufreq has many child directory for Per-CPU debugfs according to NR_CPUS number (/sys/kernel/debug/cpufreq/cpuX). > > Even you are creating this only for policy->cpu > >> Finally, Per-CPU debugfs create load_table debugfs file (/sys/kernel/debug/cpufreq/cpuX/load_table). >> >> For example, only CPU0 create sysfs directory and file (/sys/devices/system/cpu/cpu0/cpufreq) >> and then other CPUx create link of created sysfs directory by CPU0 in cpufreq_add_dev_symlink(). > > This isn't how its happening now. You aren't creating any links. You're right. This patch didn't create link for CPU1/2/3. > >> So, I'm considering whether to create link of CPUx's debugfs file except for CPU0 as sysfs file. >> - /sys/kernel/debug/cpufreq/cpu1/ >> - /sys/kernel/debug/cpufreq/cpu2/ >> - /sys/kernel/debug/cpufreq/cpu3/ > > Yes please. OK. I'll create link for CPU1,2,3 if all CPUs is included in one cluster. I explain the sequence for creating sysfs file of CPU0/1/2/3. There are difference about sysfs file. Only, CPU0 creates sysfs file and then CPU1/2/3 create a link to CPU0 sysfs file. If we want to create debugfs link for CPU1/2/3, I should have to debugfs file for CPU0 / debugfs link for CPU1/2/3 when cpufreq_register_driver() is operated. This proposal won't always remove debugfs file for cpufreq when user change cpufreq governor from ondemand/conservative to performance/powersave. So, I suggest that cpufreq core executes dbs_check_cpu() to calculate CPUx load when cpufreq governor is performance/powersave. While maintaing same cpu frequency on performance/powersave governor, there are different power-consumption according to CPUx load. I think we need to check CPUs load on peformance/powersave governor. [Flow sequence for CPU0] cpufreq_register_driver() ->subsys_interface_register() -->sif->add_dev() ---> cpufreq_add_dev() ----> cpufreq_add_policy_cpu() -----> sysfs_create_link(&dev->kboj, &policy->kobj, "cpufreq"); : Create sysfs file (/sys/devices/system/cpu/cpu0/cpufreq) [Flow sequence for CPU1/2/3] cpufreq_register_driver() ->subsys_interface_register() -->sif->add_dev() ---> cpufreq_add_dev() ----> cpufreq_add_policy_cpu() -----> cpufreq_add_dev_interface(cpu, ...) ------> cpufreq_add_dev_symlink(cpu, ...) : Create sysfs link about CPU0 sysfs file(/sys/devices/system/cpu/cpu0/cpufreq) > >> - A number of online CPU is 4 >> Time(ms) Old Freq(Hz) New Freq(Hz) CPU0 CPU1 CPU2 CPU3 >> 23165 200000 200000 2 0 0 0 >> 23370 200000 200000 2 0 0 0 >> 23575 200000 200000 2 0 1 0 >> 23640 200000 200000 5 1 1 0 >> 23780 200000 200000 3 0 1 0 >> 23830 200000 200000 7 1 0 0 >> 23985 200000 200000 1 0 0 0 >> 24190 200000 200000 2 0 1 1 >> 24385 200000 200000 2 0 0 0 >> 24485 200000 200000 6 0 1 0 >> >> - A number of online CPU is 2 >> Time(ms) Old Freq(Hz) New Freq(Hz) CPU0 CPU3 >> 37615 200000 200000 0 0 >> 37792 200000 200000 0 5 >> 38015 200000 200000 21 8 >> 38215 200000 200000 0 0 >> 38275 200000 200000 5 0 >> 38415 200000 200000 15 3 >> 38615 200000 200000 0 0 >> 38730 200000 200000 1 0 >> 38945 200000 200000 0 0 >> 39155 200000 200000 1 1 > > If you do the loop over for_each_cpu(cpu, policy->cpus), > this problem will be resolved. You will see only online cpus. > >> I'm considering whether to check the kind of cpufreq governor for creating load_table >> in cpufreq_stats or execute dbs_check_cpu() on performance/powersave governor to check >> CPUx load. If you have opinion about this, I'd like to listen it. > > Maybe create these directories and do this stuff only when > the first CPUFREQ_LOADCHECK notification is received inside > cpufreq_stats.c > > Also don't create debug/cpufreq directory unless you have any > stuff to be created within this directory. Like, don't create it > if we are using performance governor for all cpus. > If core create debugfs/cpufreq directory when first CPUFREQ_LOADCHECK notification is received inside cpufreq_stats.c, CPU1/2/3 don't send CPUFREQ_LOADCHECK notification. In result, cpufreq_stats.c couldn't create link for /sys/kernel/debug/cpufreq/cpu[1-3]. Best Regards, Chanwoo Choi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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