/proc/stat - 访客是否计入用户时间？

Question

我有一个快速的问题。在 /proc/stat 的手册页中，我不清楚：在 /proc/stat 的用户时间中是否包含来宾和来宾_nice 时间？

http://man7.org/linux/man-pages/man5/proc.5.html 手册中只有关于 /proc/[pid]/stat 的提示

https://lkml.org/lkml/2008/6/23/65 在这里，据我所知，他们在谈论 /proc/stat 和 /proc/[pid]/stat

有人可以解释一下吗？并希望指出此信息的任何来源？

Answer 1

从手册页：

This includes guest time,
guest_time (time spent running a virtual CPU, see
below), so that applications that are not aware of
the guest time field do not lose that time from
their calculations.

从内核源代码 ( .../kernel/sched/cputime.c) 中我们看到，当考虑来宾时间时，所有来宾时间也会添加到用户时间中（对于 nice 也是如此）。

/*                                                                                
 * Account guest cpu time to a process.                                           
 * @p: the process that the cpu time gets accounted to                            
 * @cputime: the cpu time spent in virtual machine since the last update          
 * @cputime_scaled: cputime scaled by cpu frequency                               
 */
static void account_guest_time(struct task_struct *p, cputime_t cputime,
                               cputime_t cputime_scaled)
{
        u64 *cpustat = kcpustat_this_cpu->cpustat;

        /* Add guest time to process. */
        p->utime += cputime;
        p->utimescaled += cputime_scaled;
        account_group_user_time(p, cputime);
        p->gtime += cputime;

        /* Add guest time to cpustat. */
        if (task_nice(p) > 0) {
                cpustat[CPUTIME_NICE] += (__force u64) cputime;
                cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
        } else {
                cpustat[CPUTIME_USER] += (__force u64) cputime;
                cpustat[CPUTIME_GUEST] += (__force u64) cputime;
        }
}

将通过被显示在用户的时间和客人时间/proc/[pid]/stat中检索.../fs/proc/array.c在do_task_stat()与调用task_cputime_adjusted()和task_gtime()其返回utime和gtime字段struct task_struct分别，虽然gtime可以进行调整：

cputime_t task_gtime(struct task_struct *t)
{
        unsigned int seq;
        cputime_t gtime;

        if (!vtime_accounting_enabled())
                return t->gtime;

        do {
                seq = read_seqcount_begin(&t->vtime_seqcount);

                gtime = t->gtime;
                if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU)
                        gtime += vtime_delta(t);

        } while (read_seqcount_retry(&t->vtime_seqcount, seq));

        return gtime;
}

[这篇文章中引用的代码来自提交29b4817 2016-08-07 Linus Torvalds Linux 4.8-rc1]