Re: [PATCH 1/7] sched: warn for high latency with TIF_NEED_RESCHED_LAZY

Re: [PATCH 1/7] sched: warn for high latency with TIF_NEED_RESCHED_LAZY

[kernel test robot]

Hi Ankur,

kernel test robot noticed the following build errors:

[auto build test ERROR on paulmck-rcu/dev]
[also build test ERROR on powerpc/next powerpc/fixes tip/sched/core linus/master v6.12-rc2 next-20241011]
[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/Ankur-Arora/sched-warn-for-high-latency-with-TIF_NEED_RESCHED_LAZY/20241010-005819
base:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev
patch link:    https://lore.kernel.org/r/20241009165411.3426937-2-ankur.a.arora%40oracle.com
patch subject: [PATCH 1/7] sched: warn for high latency with TIF_NEED_RESCHED_LAZY
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20241013/202410131726.Gi9qvUP8-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241013/202410131726.Gi9qvUP8-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/202410131726.Gi9qvUP8-lkp@intel.com/

All errors (new ones prefixed by >>):

>> kernel/sched/core.c:5528:27: error: call to undeclared function 'tif_need_resched_lazy'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    5528 |         if ((!need_resched() && !tif_need_resched_lazy()) || !latency_warn_ms)
         |                                  ^
   kernel/sched/core.c:5528:27: note: did you mean 'tif_need_resched'?
   include/linux/thread_info.h:182:29: note: 'tif_need_resched' declared here
     182 | static __always_inline bool tif_need_resched(void)
         |                             ^
   1 error generated.


vim +/tif_need_resched_lazy +5528 kernel/sched/core.c

  5517	
  5518	#ifdef CONFIG_SCHED_DEBUG
  5519	static u64 cpu_resched_latency(struct rq *rq)
  5520	{
  5521		int latency_warn_ms = READ_ONCE(sysctl_resched_latency_warn_ms);
  5522		u64 resched_latency, now = rq_clock(rq);
  5523		static bool warned_once;
  5524	
  5525		if (sysctl_resched_latency_warn_once && warned_once)
  5526			return 0;
  5527	
> 5528		if ((!need_resched() && !tif_need_resched_lazy()) || !latency_warn_ms)
  5529			return 0;
  5530	
  5531		if (system_state == SYSTEM_BOOTING)
  5532			return 0;
  5533	
  5534		if (!rq->last_seen_need_resched_ns) {
  5535			rq->last_seen_need_resched_ns = now;
  5536			rq->ticks_without_resched = 0;
  5537			return 0;
  5538		}
  5539	
  5540		rq->ticks_without_resched++;
  5541		resched_latency = now - rq->last_seen_need_resched_ns;
  5542		if (resched_latency <= latency_warn_ms * NSEC_PER_MSEC)
  5543			return 0;
  5544	
  5545		warned_once = true;
  5546	
  5547		return resched_latency;
  5548	}
  5549	

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