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

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

[Chen Ridong]

In the function cgroup_base_stat_cputime_show, there are five
instances of #ifdef, which makes the code not concise.
To address this, add the function cgroup_force_idle_show
to make the code more succinct.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
---
 kernel/cgroup/rstat.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index fb8b49437573..22bb4e9050f0 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -594,49 +594,47 @@ static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
 	}
 }
 
+
+static void cgroup_force_idle_show(struct seq_file *seq, struct cgroup_base_stat *bstat)
+{
+#ifdef CONFIG_SCHED_CORE
+	u64 forceidle_time = bstat->forceidle_sum;
+
+	do_div(forceidle_time, NSEC_PER_USEC);
+	seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time);
+#endif
+}
+
 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
+		bstat = cgrp->bstat;
 		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
 	}
 
 	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, &bstat);
 }
 
 /* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
-- 
2.34.1

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

[Tejun Heo]

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.

-- 
tejun

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

[chenridong]

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);
  }