Re: [PATCH V2 2/2] sched: Reduce the default slice to avoid tasks getting an extra tick

[kernel test robot <lkp@intel.com>]

Hi zihan,

kernel test robot noticed the following build errors:

[auto build test ERROR on tip/sched/core]
[also build test ERROR on peterz-queue/sched/core linus/master v6.14-rc1 next-20250207]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/zihan-zhou/sched-Reduce-the-default-slice-to-avoid-tasks-getting-an-extra-tick/20250207-142556
base:   tip/sched/core
patch link:    https://lore.kernel.org/r/20250207062402.33725-1-15645113830zzh%40gmail.com
patch subject: [PATCH V2 2/2] sched: Reduce the default slice to avoid tasks getting an extra tick
config: i386-randconfig-141-20250208 (https://download.01.org/0day-ci/archive/20250208/202502080831.VwRnAlxo-lkp@intel.com/config)
compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250208/202502080831.VwRnAlxo-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502080831.VwRnAlxo-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from kernel/sched/build_utility.c:72:
>> kernel/sched/debug.c:193:2: error: call to undeclared function 'sched_update_scaling'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     193 |         sched_update_scaling();
         |         ^
   1 error generated.


vim +/sched_update_scaling +193 kernel/sched/debug.c

   168	
   169	
   170	static ssize_t sched_base_slice_write(struct file *filp, const char __user *ubuf,
   171					   size_t cnt, loff_t *ppos)
   172	{
   173		char buf[16];
   174		unsigned int base_slice;
   175	
   176		if (cnt > 15)
   177			cnt = 15;
   178	
   179		if (copy_from_user(&buf, ubuf, cnt))
   180			return -EFAULT;
   181		buf[cnt] = '\0';
   182	
   183		if (kstrtouint(buf, 10, &base_slice))
   184			return -EINVAL;
   185	
   186	
   187		base_slice = clamp_t(u64, base_slice,
   188						NSEC_PER_MSEC/10,   /* HZ=1000 * 10 */
   189						NSEC_PER_MSEC*100); /* HZ=100  / 10 */
   190	
   191		sysctl_sched_base_slice = base_slice;
   192	
 > 193		sched_update_scaling();
   194	
   195		*ppos += cnt;
   196		return cnt;
   197	}
   198	

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