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    SubjectRe: [PATCH v7 4/6] rcu: Add RCU stall diagnosis information
    On Fri, Nov 11, 2022 at 09:07:07PM +0800, Zhen Lei wrote:
    > @@ -262,6 +279,8 @@ struct rcu_data {
    > short rcu_onl_gp_flags; /* ->gp_flags at last online. */
    > unsigned long last_fqs_resched; /* Time of last rcu_resched(). */
    > unsigned long last_sched_clock; /* Jiffies of last rcu_sched_clock_irq(). */
    > + struct rcu_snap_record snap_record; /* Snapshot of core stats at half of */
    > + /* the first RCU stall timeout */

    This should be under #ifdef CONFIG_RCU_CPU_STALL_CPUTIME

    > +static void print_cpu_stat_info(int cpu)
    > +{
    > + struct rcu_snap_record rsr, *rsrp;
    > + struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
    > + struct kernel_cpustat *kcsp = &kcpustat_cpu(cpu);
    > +
    > + if (!rcu_cpu_stall_cputime)
    > + return;
    > +
    > + rsrp = &rdp->snap_record;
    > + if (rsrp->gp_seq != rdp->gp_seq)
    > + return;
    > +
    > + rsr.cputime_irq = kcpustat_field(kcsp, CPUTIME_IRQ, cpu);
    > + rsr.cputime_softirq = kcpustat_field(kcsp, CPUTIME_SOFTIRQ, cpu);
    > + rsr.cputime_system = kcpustat_field(kcsp, CPUTIME_SYSTEM, cpu);
    > +
    > + pr_err("\t hardirqs softirqs csw/system\n");
    > + pr_err("\t number: %8ld %10d %12lld\n",
    > + kstat_cpu_irqs_sum(cpu) - rsrp->nr_hardirqs,
    > + kstat_cpu_softirqs_sum(cpu) - rsrp->nr_softirqs,
    > + nr_context_switches_cpu(cpu) - rsrp->nr_csw);
    > + pr_err("\tcputime: %8lld %10lld %12lld ==> %lld(ms)\n",
    > + div_u64(rsr.cputime_irq - rsrp->cputime_irq, NSEC_PER_MSEC),
    > + div_u64(rsr.cputime_softirq - rsrp->cputime_softirq, NSEC_PER_MSEC),
    > + div_u64(rsr.cputime_system - rsrp->cputime_system, NSEC_PER_MSEC),
    > + jiffies64_to_msecs(jiffies - rsrp->jiffies));

    jiffies_to_msecs() should be enough.

    Thanks.

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