sched/rt: Remove unnecessary CONFIG_RT_GROUP_SCHED in rt_se_prio()

PATCH In review Muchun Song 2 participants 3 messages Oct 30, 2018 Scheduler

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Muchun Song

author

2018-10-30 14:45 UTC #0 lore raw

PATCH 1/1 sched/rt: Remove unnecessary CONFIG_RT_GROUP_SCHED in rt_se_prio()

When CONFIG_RT_GROUP_SCHED is not configured, group_rt_rq() will return NULL. With this patch applied, we also can get the same result. Because the compiler will help us optimize the code.

So, we can remove unnecessary CONFIG_RT_GROUP_SCHED in rt_se_prio().

Signed-off-by Muchun Song <[email protected]>

---
 kernel/sched/rt.c | 2 --
 1 file changed, 2 deletions(-)

kernel/sched/rt.c +0 -2

index a21ea6021929..47b4800761db 100644
@@ -894,12 +894,10 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
 
 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
 {
-#ifdef CONFIG_RT_GROUP_SCHED
 	struct rt_rq *rt_rq = group_rt_rq(rt_se);
 
 	if (rt_rq)
 		return rt_rq->highest_prio.curr;
-#endif
 
 	return rt_task_of(rt_se)->prio;
 }

Signature · 1 line

2.17.1

kbuild test robot

build bot

2018-10-30 15:14 UTC #1 lore raw

Thank you for the patch! Yet something to improve:

Hi Muchun,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on tip/sched/core]
[also build test ERROR on v4.19 next-20181030]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Muchun-Song/sched-rt-Remove-unnecessary-CONFIG_RT_GROUP_SCHED-in-rt_se_prio/20181030-225925
config: i386-randconfig-x002-201843 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0 reproduce:

        # save the attached .config to linux build tree
        make ARCH=i386

All errors (new ones prefixed by >>):

kernel/sched/rt.c: In function 'rt_se_prio':

>> kernel/sched/rt.c:900:15: error: 'struct rt_rq' has no member named 'highest_prio'
      return rt_rq->highest_prio.curr;
                  ^~

vim +900 kernel/sched/rt.c

ac086bc2 kernel/sched_rt.c Peter Zijlstra  2008-04-19  894  
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  895  static inline int rt_se_prio(struct sched_rt_entity *rt_se)
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  896  {
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  897  	struct rt_rq *rt_rq = group_rt_rq(rt_se);
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  898  
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  899  	if (rt_rq)
e864c499 kernel/sched_rt.c Gregory Haskins 2008-12-29 @900  		return rt_rq->highest_prio.curr;
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  901  
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  902  	return rt_task_of(rt_se)->prio;
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  903  }
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  904

:::::: The code at line 900 was first introduced by commit
:::::: e864c499d9e57805ae1f9e7ea404dd223759cd53 sched: track the next-highest priority on each runqueue

:::::: TO: Gregory Haskins <[email protected]>
:::::: CC: Gregory Haskins <[email protected]>

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

宋牧春

author

2018-10-30 15:42 UTC #2 lore raw

Hi,

I am sorry that I did not consider CONFIG_SMP is also not configured. In this case, 'struct rt_rq' has no member named 'highest_prio'. So, I I understand why the code here needs CONFIG_RT_GROUP_SCHED. When CONFIG_SMP or CONFIG_RT_GROUP_SCHED is configured, 'struct rt_rq' will have member named 'highest_prio'.

So, this patch does't make sense.

Quoted 46 lines · kbuild test robot <[email protected]> 于2018年10月30日周二下午11:14写道：

Hi Muchun,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on tip/sched/core]
[also build test ERROR on v4.19 next-20181030]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Muchun-Song/sched-rt-Remove-unnecessary-CONFIG_RT_GROUP_SCHED-in-rt_se_prio/20181030-225925
config: i386-randconfig-x002-201843 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0 reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386
All errors (new ones prefixed by >>):
kernel/sched/rt.c: In function 'rt_se_prio':
Quoted 1 line
Quoted 1 line
kernel/sched/rt.c:900:15: error: 'struct rt_rq' has no member named 'highest_prio'
      return rt_rq->highest_prio.curr;
                  ^~
vim +900 kernel/sched/rt.c
ac086bc2 kernel/sched_rt.c Peter Zijlstra  2008-04-19  894
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  895  static inline int rt_se_prio(struct sched_rt_entity *rt_se)
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  896  {
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  897      struct rt_rq *rt_rq = group_rt_rq(rt_se);
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  898
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  899      if (rt_rq)
e864c499 kernel/sched_rt.c Gregory Haskins 2008-12-29 @900              return rt_rq->highest_prio.curr;
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  901
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  902      return rt_task_of(rt_se)->prio;
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  903  }
6f505b16 kernel/sched_rt.c Peter Zijlstra  2008-01-25  904
:::::: The code at line 900 was first introduced by commit
:::::: e864c499d9e57805ae1f9e7ea404dd223759cd53 sched: track the next-highest priority on each runqueue
:::::: TO: Gregory Haskins <[email protected]>
:::::: CC: Gregory Haskins <[email protected]>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation