tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/debug head: 6ee7724cc02b834ea8f67c65d5d30a62e9d952a3 commit: 6ee7724cc02b834ea8f67c65d5d30a62e9d952a3 [11/11] sched: Warn on long periods of pending need_resched config: arm-randconfig-r003-20210330 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 3a6365a439ede4b7c65076bb42b1b7dbf72216b5) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install arm cross compiling tool for clang build # apt-get install binutils-arm-linux-gnueabi # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?... git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git git fetch --no-tags peterz-queue sched/debug git checkout 6ee7724cc02b834ea8f67c65d5d30a62e9d952a3 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): if (now < resched_boot_quiet_sec * NSEC_PER_SEC) ^ kernel/sched/core.c:2910:20: warning: unused function 'rq_has_pinned_tasks' [-Wunused-function] static inline bool rq_has_pinned_tasks(struct rq *rq) ^ kernel/sched/core.c:4772:20: warning: unused function 'sched_tick_start' [-Wunused-function] static inline void sched_tick_start(int cpu) { } ^ kernel/sched/core.c:4773:20: warning: unused function 'sched_tick_stop' [-Wunused-function] static inline void sched_tick_stop(int cpu) { } ^ 4 warnings generated. vim +/long +4558 kernel/sched/core.c 4543 4544 #ifdef CONFIG_SCHED_DEBUG 4545 static u64 resched_latency_check(struct rq *rq) 4546 { 4547 int latency_warn_ms = READ_ONCE(sysctl_resched_latency_warn_ms); 4548 u64 need_resched_latency, now = rq_clock(rq); 4549 static bool warned_once; 4550 4551 if (sysctl_resched_latency_warn_once && warned_once) 4552 return 0; 4553 4554 if (!need_resched() || WARN_ON_ONCE(latency_warn_ms < 2)) 4555 return 0; 4556 4557 /* Disable this warning for the first few mins after boot */ 4559 return 0; 4560 4561 if (!rq->last_seen_need_resched_ns) { 4562 rq->last_seen_need_resched_ns = now; 4563 rq->ticks_without_resched = 0; 4564 return 0; 4565 } 4566 4567 rq->ticks_without_resched++; 4568 need_resched_latency = now - rq->last_seen_need_resched_ns; 4569 if (need_resched_latency <= latency_warn_ms * NSEC_PER_MSEC) 4570 return 0; 4571 4572 warned_once = true; 4573 4574 return need_resched_latency; 4575 } 4576 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org