Re: [PATCH v2 -next] cgroup/rstat: add force idle show helper

[chenridong <chenridong@xxxxxxxxxx>]

On 2024/7/3 1:19, Tejun Heo wrote:
> Hello,
>
> On Tue, Jul 02, 2024 at 02:28:22AM +0000, Chen Ridong wrote:
> ...
> >   	if (cgroup_parent(cgrp)) {
> >   		cgroup_rstat_flush_hold(cgrp);
> >   		usage = cgrp->bstat.cputime.sum_exec_runtime;
> >   		cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
> >   			       &utime, &stime);
> > -#ifdef CONFIG_SCHED_CORE
> > -		forceidle_time = cgrp->bstat.forceidle_sum;
> > -#endif
> > +		bstat = cgrp->bstat;
>
> Please don't copy non-trivial struct like this. Maybe add a pointer which
> points to the bstat to use?
>
> Thanks.

I don't wanna add a pointer. If I add pointer,to prevent the situation 
where a variable is unused when CONFIG_SCHED_CORE is disable, I have to 
add #ifdef CONFIG_SCHED_CORE again.
We do not actually need to define bstat. The cgrp->bstat of root is not 
actually used, maybe we can simply use cgrp->bstat directly as below.

void cgroup_base_stat_cputime_show(struct seq_file *seq)
 {
        struct cgroup *cgrp = seq_css(seq)->cgroup;
        u64 usage, utime, stime;
-       struct cgroup_base_stat bstat;
-#ifdef CONFIG_SCHED_CORE
-       u64 forceidle_time;
-#endif

        if (cgroup_parent(cgrp)) {
                cgroup_rstat_flush_hold(cgrp);
                usage = cgrp->bstat.cputime.sum_exec_runtime;
                cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
                               &utime, &stime);
-#ifdef CONFIG_SCHED_CORE
-               forceidle_time = cgrp->bstat.forceidle_sum;
-#endif
                cgroup_rstat_flush_release(cgrp);
        } else {
-               root_cgroup_cputime(&bstat);
-               usage = bstat.cputime.sum_exec_runtime;
-               utime = bstat.cputime.utime;
-               stime = bstat.cputime.stime;
-#ifdef CONFIG_SCHED_CORE
-               forceidle_time = bstat.forceidle_sum;
-#endif
+               root_cgroup_cputime(&cgrp->bstat);
+               usage = cgrp->bstat.cputime.sum_exec_runtime;
+               utime = cgrp->bstat.cputime.utime;
+               stime = cgrp->bstat.cputime.stime;
        }

        do_div(usage, NSEC_PER_USEC);
        do_div(utime, NSEC_PER_USEC);
        do_div(stime, NSEC_PER_USEC);
-#ifdef CONFIG_SCHED_CORE
-       do_div(forceidle_time, NSEC_PER_USEC);
-#endif

        seq_printf(seq, "usage_usec %llu\n"
                   "user_usec %llu\n"
                   "system_usec %llu\n",
                   usage, utime, stime);

-#ifdef CONFIG_SCHED_CORE
-       seq_printf(seq, "core_sched.force_idle_usec %llu\n", 
forceidle_time);
-#endif
+       cgroup_force_idle_show(seq, &cgrp->bstat);
 }