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    SubjectRe: [PATCH v2 03/14] Move /proc/stat logic inside sched.c
    On 11/11/2011 11:35 PM, Paul Turner wrote:
    > On 11/01/2011 02:19 PM, Glauber Costa wrote:
    >> This patch moves all of the /proc/stat display code inside
    >> sched.c. The goal is to later on, have a different version
    >> of it per-cgroup. In containers environment, this is useful
    >> to give each container a different and independent view of
    >> the statistics displayed in this file.
    >>
    >> Signed-off-by: Glauber Costa<glommer@parallels.com>
    >> ---
    >> fs/proc/stat.c | 139 +-----------------------------------------------
    >> include/linux/sched.h | 1 +
    >> kernel/sched.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++
    >> 3 files changed, 144 insertions(+), 138 deletions(-)
    >>
    >
    > This feels a little contrived. sched.c isn't the right place for much of
    > this code. Why do you want to move it all instead of exporting the
    > functionality (e.g. remove static?).

    Because later on in the series I start using task_group, which is a
    scheduler internal data structure (Since the very goal here is achieving
    per cgroup data.

    It seemed to me better to do this way - as much as I agree with you that
    a lot here may not belong in sched.c - than to use external functions.
    Since all we have outside sched.c is a task_struct,
    we'd have to derive a task_group from it every time. Also,
    as you can see in the followup patches, which task_group to use depends
    on the caller and possibly some runtime variables. So the computation is
    not as trivially fast as just getting a field in a structure.


    >> diff --git a/kernel/sched.c b/kernel/sched.c
    >> index e78e1aa..3f42916 100644
    >> --- a/kernel/sched.c
    >> +++ b/kernel/sched.c
    >> @@ -71,6 +71,7 @@
    >> #include<linux/ctype.h>
    >> #include<linux/ftrace.h>
    >> #include<linux/slab.h>
    >> +#include<linux/tick.h>
    >>
    >> #include<asm/tlb.h>
    >> #include<asm/irq_regs.h>
    >> @@ -9494,6 +9495,147 @@ struct cgroup_subsys cpu_cgroup_subsys = {
    >>
    >> #endif /* CONFIG_CGROUP_SCHED */
    >>
    >> +#ifndef fi
    >> +#define arch_irq_stat_cpu(cpu) 0
    >> +#endif
    >> +#ifndef arch_irq_stat
    >> +#define arch_irq_stat() 0
    >> +#endif
    >> +#ifndef arch_idle_time
    >> +#define arch_idle_time(cpu) 0
    >> +#endif
    >> +
    >> +static u64 get_idle_time(int cpu)
    >> +{
    >> + u64 idle, idle_time = get_cpu_idle_time_us(cpu, NULL);
    >> +
    >> + if (idle_time == -1ULL) {
    >> + /* !NO_HZ so we can rely on cpustat.idle */
    >> + idle = kstat_cpu(cpu).cpustat[IDLE];
    >> + idle += arch_idle_time(cpu);
    >> + } else
    >> + idle = usecs_to_cputime(idle_time);
    >> +
    >> + return idle;
    >> +}
    >> +
    >> +static u64 get_iowait_time(int cpu)
    >> +{
    >> + u64 iowait, iowait_time = get_cpu_iowait_time_us(cpu, NULL);
    >> +
    >> + if (iowait_time == -1ULL)
    >> + /* !NO_HZ so we can rely on cpustat.iowait */
    >> + iowait = kstat_cpu(cpu).cpustat[IOWAIT];
    >> + else
    >> + iowait = usecs_to_cputime(iowait_time);
    >> +
    >> + return iowait;
    >> +}
    >> +
    >> +int cpu_cgroup_proc_stat(struct seq_file *p)
    >> +{
    >> + int i, j;
    >> + unsigned long jif;
    >> + u64 user, nice, system, idle, iowait, irq, softirq, steal;
    >> + u64 guest, guest_nice;
    >> + u64 sum = 0;
    >> + u64 sum_softirq = 0;
    >> + unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
    >> + struct timespec boottime;
    >> +
    >> + user = nice = system = idle = iowait =
    >> + irq = softirq = steal = 0;
    >> + guest = guest_nice = 0;
    >> + getboottime(&boottime);
    >> + jif = boottime.tv_sec;
    >> +
    >> + for_each_possible_cpu(i) {
    >> + user += kstat_cpu(i).cpustat[USER];
    >> + nice += kstat_cpu(i).cpustat[NICE];
    >> + system += kstat_cpu(i).cpustat[SYSTEM];
    >> + idle += get_idle_time(i);
    >> + iowait += get_iowait_time(i);
    >> + irq += kstat_cpu(i).cpustat[IRQ];
    >> + softirq += kstat_cpu(i).cpustat[SOFTIRQ];
    >> + steal += kstat_cpu(i).cpustat[STEAL];
    >> + guest += kstat_cpu(i).cpustat[GUEST];
    >> + guest_nice += kstat_cpu(i).cpustat[GUEST_NICE];
    >> +
    >> + for (j = 0; j< NR_SOFTIRQS; j++) {
    >> + unsigned int softirq_stat = kstat_softirqs_cpu(j, i);
    >> +
    >> + per_softirq_sums[j] += softirq_stat;
    >> + sum_softirq += softirq_stat;
    >> + }
    >> + }
    >> + sum += arch_irq_stat();
    >> +
    >> + seq_printf(p, "cpu %llu %llu %llu %llu %llu %llu %llu %llu %llu "
    >> + "%llu\n",
    >> + (unsigned long long)cputime64_to_clock_t(user),
    >> + (unsigned long long)cputime64_to_clock_t(nice),
    >> + (unsigned long long)cputime64_to_clock_t(system),
    >> + (unsigned long long)cputime64_to_clock_t(idle),
    >> + (unsigned long long)cputime64_to_clock_t(iowait),
    >> + (unsigned long long)cputime64_to_clock_t(irq),
    >> + (unsigned long long)cputime64_to_clock_t(softirq),
    >> + (unsigned long long)cputime64_to_clock_t(steal),
    >> + (unsigned long long)cputime64_to_clock_t(guest),
    >> + (unsigned long long)cputime64_to_clock_t(guest_nice));
    >> + for_each_online_cpu(i) {
    >> + /* Copy values here to work around gcc-2.95.3, gcc-2.96 */
    >
    > GCC 3.2 is the listed current minimum requirement. If this code is being
    > revisited this could be cleaned up.
    >
    >> + user = kstat_cpu(i).cpustat[USER];
    >> + nice = kstat_cpu(i).cpustat[NICE];
    >> + system = kstat_cpu(i).cpustat[SYSTEM];
    >> + idle = get_idle_time(i);
    >> + iowait = get_iowait_time(i);
    >> + irq = kstat_cpu(i).cpustat[IRQ];
    >> + softirq = kstat_cpu(i).cpustat[SOFTIRQ];
    >> + steal = kstat_cpu(i).cpustat[STEAL];
    >> + guest = kstat_cpu(i).cpustat[GUEST];
    >> + guest_nice = kstat_cpu(i).cpustat[GUEST_NICE];
    >> + seq_printf(p,
    >> + "cpu%d %llu %llu %llu %llu %llu %llu %llu %llu %llu "
    >> + "%llu\n",
    >> + i,
    >> + (unsigned long long)cputime64_to_clock_t(user),
    >> + (unsigned long long)cputime64_to_clock_t(nice),
    >> + (unsigned long long)cputime64_to_clock_t(system),
    >> + (unsigned long long)cputime64_to_clock_t(idle),
    >> + (unsigned long long)cputime64_to_clock_t(iowait),
    >> + (unsigned long long)cputime64_to_clock_t(irq),
    >> + (unsigned long long)cputime64_to_clock_t(softirq),
    >> + (unsigned long long)cputime64_to_clock_t(steal),
    >> + (unsigned long long)cputime64_to_clock_t(guest),
    >> + (unsigned long long)cputime64_to_clock_t(guest_nice));
    >> + }
    >> + seq_printf(p, "intr %llu", (unsigned long long)sum);
    >> +
    >> + /* sum again ? it could be updated? */
    >> + for_each_irq_nr(j)
    >> + seq_printf(p, " %u", kstat_irqs(j));
    >> +
    >> + seq_printf(p,
    >> + "\nctxt %llu\n"
    >> + "btime %lu\n"
    >> + "processes %lu\n"
    >> + "procs_running %lu\n"
    >> + "procs_blocked %lu\n",
    >> + nr_context_switches(),
    >> + (unsigned long)jif,
    >> + total_forks,
    >> + nr_running(),
    >> + nr_iowait());
    >> +
    >> + seq_printf(p, "softirq %llu", (unsigned long long)sum_softirq);
    >> +
    >> + for (i = 0; i< NR_SOFTIRQS; i++)
    >> + seq_printf(p, " %u", per_softirq_sums[i]);
    >> + seq_putc(p, '\n');
    >> +
    >> + return 0;
    >> +}
    >> +
    >> #ifdef CONFIG_CGROUP_CPUACCT
    >>
    >> /*
    >



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