Subject: Provide individual CPU usage measurement based on idle time From: Carsten Emde Date: Sun, 22 Apr 2012 15:19:46 +0100 The various methods to determine CPU usage and load have a number of disadvantages (see also Documentation/cpu-load.txt), and a straight-forward method to gain usage information about a particular CPU is lacking. However, in the context of setting CPU affinity and isolation, it is often required to monitor the effective usage ratio of a CPU. This patch adds an additional CPU usage measuring method that is based on idle time processing. The data are available for every CPU in /proc/cpuload/cpuN/data in the format " ". The counters can be reset by writing to /proc/cpuload/resetall for all CPUs and to /proc/cpuload/cpuN/reset for a particular CPU, respectively. To calculate the CPU usage since the most recent reset, divide the runtime by the sum of runtime plus idletime, e.g. # for i in `ls -1d /proc/cpuload/cpu* | sort -nk1.18` > do > echo "$i: `awk '{ print (100.0*$2) / ($1+$2)"%" }' <$i/data`" > echo 1 >$i/reset > done /proc/cpuload/cpu0: 72.0048% /proc/cpuload/cpu1: 5.49522% /proc/cpuload/cpu2: 0.27916% /proc/cpuload/cpu3: 32.3493% Signed-off-by: Carsten Emde --- init/Kconfig | 12 +++ kernel/sched/Makefile | 1 kernel/sched/core.c | 23 ++++++ kernel/sched/cpu_idleruntime.c | 136 +++++++++++++++++++++++++++++++++++++++++ kernel/sched/sched.h | 8 ++ 5 files changed, 180 insertions(+) Index: linux-3.12.19-rt30/init/Kconfig =================================================================== --- linux-3.12.19-rt30.orig/init/Kconfig +++ linux-3.12.19-rt30/init/Kconfig @@ -407,6 +407,18 @@ config BSD_PROCESS_ACCT_V3 for processing it. A preliminary version of these tools is available at . +config CPU_IDLERUNTIME + bool "Provide individual CPU usage measurement based on idle processing" + help + If you say Y here, individual CPU usage data will be provided that are + based on idle processing. The data are available for every CPU in + /proc/cpuload/cpuN/data in the format " ". The + counters can be reset by writing to /proc/cpuload/resetall for all + CPUs and to /proc/cpuload/cpuN/reset for a particular CPU, + respectively. To calculate the usage since the most recent reset, + the runtime must be devided by the sum of idletime plus runtime, e.g. + cat /proc/cpuload/cpu0/data | awk '{print (100.0*$2) / ($1+$2)"%"}' + config TASKSTATS bool "Export task/process statistics through netlink" depends on NET Index: linux-3.12.19-rt30/kernel/sched/Makefile =================================================================== --- linux-3.12.19-rt30.orig/kernel/sched/Makefile +++ linux-3.12.19-rt30/kernel/sched/Makefile @@ -15,5 +15,6 @@ obj-y += core.o proc.o clock.o cputime.o obj-$(CONFIG_SMP) += cpupri.o obj-$(CONFIG_SCHED_AUTOGROUP) += auto_group.o obj-$(CONFIG_SCHEDSTATS) += stats.o +obj-$(CONFIG_CPU_IDLERUNTIME) += cpu_idleruntime.o obj-$(CONFIG_SCHED_DEBUG) += debug.o obj-$(CONFIG_CGROUP_CPUACCT) += cpuacct.o Index: linux-3.12.19-rt30/kernel/sched/core.c =================================================================== --- linux-3.12.19-rt30.orig/kernel/sched/core.c +++ linux-3.12.19-rt30/kernel/sched/core.c @@ -1897,6 +1897,37 @@ prepare_task_switch(struct rq *rq, struc fire_sched_out_preempt_notifiers(prev, next); prepare_lock_switch(rq, next); prepare_arch_switch(next); +#ifdef CONFIG_CPU_IDLERUNTIME + if (is_idle_task(next)) { + int cpu = raw_smp_processor_id(); + + if (per_cpu(idlestop, cpu)) { + unsigned long flags; + + raw_spin_lock_irqsave(&per_cpu(idleruntime_lock, cpu), + flags); + per_cpu(idlestart, cpu) = cpu_clock(cpu); + per_cpu(runtime, cpu) += + per_cpu(idlestart, cpu) - per_cpu(idlestop, cpu); + raw_spin_unlock_irqrestore(&per_cpu(idleruntime_lock, + cpu), flags); + } + } else if (is_idle_task(prev)) { + int cpu = raw_smp_processor_id(); + + if (per_cpu(idlestart, cpu)) { + unsigned long flags; + + raw_spin_lock_irqsave(&per_cpu(idleruntime_lock, cpu), + flags); + per_cpu(idlestop, cpu) = cpu_clock(cpu); + per_cpu(idletime, cpu) += + per_cpu(idlestop, cpu) - per_cpu(idlestart, cpu); + raw_spin_unlock_irqrestore(&per_cpu(idleruntime_lock, + cpu), flags); + } + } +#endif } /** Index: linux-3.12.19-rt30/kernel/sched/cpu_idleruntime.c =================================================================== --- /dev/null +++ linux-3.12.19-rt30/kernel/sched/cpu_idleruntime.c @@ -0,0 +1,138 @@ +/* + cpu_idleruntime.c: provide CPU usage data based on idle processing + + Copyright (C) 2012 Carsten Emde + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License + as published by the Free Software Foundation; either version 2 + of the License, or (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. +*/ + +#include +#include + +#include "sched.h" + +DEFINE_PER_CPU(unsigned long long, idlestart); +DEFINE_PER_CPU(unsigned long long, idlestop); +DEFINE_PER_CPU(unsigned long long, idletime); +DEFINE_PER_CPU(unsigned long long, runtime); +DEFINE_PER_CPU(raw_spinlock_t, idleruntime_lock); + +static int idleruntime_show(struct seq_file *m, void *v) +{ + unsigned long cpu = (unsigned long) m->private; + unsigned long long now; + unsigned long flags; + + raw_spin_lock_irqsave(&per_cpu(idleruntime_lock, cpu), flags); + + /* Update runtime counter */ + now = cpu_clock(cpu); + per_cpu(runtime, cpu) += now - per_cpu(idlestop, cpu); + per_cpu(idlestop, cpu) = now; + + seq_printf(m, "%llu %llu\n", per_cpu(idletime, cpu), + per_cpu(runtime, cpu)); + + raw_spin_unlock_irqrestore(&per_cpu(idleruntime_lock, cpu), flags); + + return 0; +} + +static inline void idleruntime_reset1(int cpu) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&per_cpu(idleruntime_lock, cpu), flags); + per_cpu(idletime, cpu) = per_cpu(runtime, cpu) = 0; + per_cpu(idlestop, cpu) = cpu_clock(cpu); + raw_spin_unlock_irqrestore(&per_cpu(idleruntime_lock, cpu), flags); +} + +static ssize_t idleruntime_reset(struct file *file, const char __user *buffer, + size_t len, loff_t *offset) +{ + unsigned long cpu = (unsigned long) PDE_DATA(file_inode(file)); + + idleruntime_reset1(cpu); + return len; +} + +static ssize_t idleruntime_resetall(struct file *file, + const char __user *buffer, + size_t len, loff_t *offset) +{ + unsigned long cpu; + + for_each_online_cpu(cpu) + idleruntime_reset1(cpu); + return len; +} + +static const struct file_operations idleruntime_resetall_fops = { + .write = idleruntime_resetall, + .release = single_release, +}; + +static int idleruntime_open(struct inode *inode, struct file *file) +{ + return single_open(file, idleruntime_show, PDE_DATA(inode)); +} + +static const struct file_operations idleruntime_fops = { + .open = idleruntime_open, + .read = seq_read, + .llseek = seq_lseek, + .write = idleruntime_reset, + .release = single_release, +}; + +static int __init proc_idleruntime_init(void) +{ + unsigned long cpu; + struct proc_dir_entry *root_idleruntime_dir; + + root_idleruntime_dir = proc_mkdir("idleruntime", NULL); + if (!root_idleruntime_dir) + return 0; + + if (!proc_create("resetall", S_IWUGO, root_idleruntime_dir, + &idleruntime_resetall_fops)) + return 0; + + for_each_possible_cpu(cpu) { + char name[32]; + struct proc_dir_entry *idleruntime_cpudir; + + raw_spin_lock_init(&per_cpu(idleruntime_lock, cpu)); + + snprintf(name, sizeof(name), "cpu%lu", cpu); + idleruntime_cpudir = proc_mkdir(name, root_idleruntime_dir); + if (!idleruntime_cpudir) + return 0; + + if (!proc_create_data("data", S_IRUGO, idleruntime_cpudir, + &idleruntime_fops, (void *) cpu)) + return 0; + + if (!proc_create_data("reset", S_IWUGO, idleruntime_cpudir, + &idleruntime_fops, (void *) cpu)) { + remove_proc_entry("data", idleruntime_cpudir); + return 0; + } + } + return 0; +} + +module_init(proc_idleruntime_init); Index: linux-3.12.19-rt30/kernel/sched/sched.h =================================================================== --- linux-3.12.19-rt30.orig/kernel/sched/sched.h +++ linux-3.12.19-rt30/kernel/sched/sched.h @@ -552,6 +552,14 @@ static inline u64 rq_clock_task(struct r return rq->clock_task; } +#ifdef CONFIG_CPU_IDLERUNTIME +extern DEFINE_PER_CPU(unsigned long long, idlestart); +extern DEFINE_PER_CPU(unsigned long long, idlestop); +extern DEFINE_PER_CPU(unsigned long long, idletime); +extern DEFINE_PER_CPU(unsigned long long, runtime); +extern DEFINE_PER_CPU(raw_spinlock_t, idleruntime_lock); +#endif + #ifdef CONFIG_SMP #define rcu_dereference_check_sched_domain(p) \