Re: [PATCH] hrtimer: avoid retrigger_next_event IPI

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

[-- Attachment #1: Type: text/plain, Size: 6205 bytes --]

Hi Marcelo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/timers/core]
[also build test WARNING on linux/master linus/master v5.12-rc6 next-20210407]
[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]

url:    https://github.com/0day-ci/linux/commits/Marcelo-Tosatti/hrtimer-avoid-retrigger_next_event-IPI/20210407-233005
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git d4c7c28806616809e3baa0b7cd8c665516b2726d
config: arm64-randconfig-r032-20210407 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project c060945b23a1c54d4b2a053ff4b093a2277b303d)
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 arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://github.com/0day-ci/linux/commit/defd4db9d63d1f16e3e21862bd9c9105a9f6a7e9
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Marcelo-Tosatti/hrtimer-avoid-retrigger_next_event-IPI/20210407-233005
        git checkout defd4db9d63d1f16e3e21862bd9c9105a9f6a7e9
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   kernel/time/hrtimer.c:120:21: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [CLOCK_REALTIME]        = HRTIMER_BASE_REALTIME,
                                     ^~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:118:27: note: previous initialization is here
           [0 ... MAX_CLOCKS - 1]  = HRTIMER_MAX_CLOCK_BASES,
                                     ^~~~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:121:22: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [CLOCK_MONOTONIC]       = HRTIMER_BASE_MONOTONIC,
                                     ^~~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:118:27: note: previous initialization is here
           [0 ... MAX_CLOCKS - 1]  = HRTIMER_MAX_CLOCK_BASES,
                                     ^~~~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:122:21: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [CLOCK_BOOTTIME]        = HRTIMER_BASE_BOOTTIME,
                                     ^~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:118:27: note: previous initialization is here
           [0 ... MAX_CLOCKS - 1]  = HRTIMER_MAX_CLOCK_BASES,
                                     ^~~~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:123:17: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [CLOCK_TAI]             = HRTIMER_BASE_TAI,
                                     ^~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:118:27: note: previous initialization is here
           [0 ... MAX_CLOCKS - 1]  = HRTIMER_MAX_CLOCK_BASES,
                                     ^~~~~~~~~~~~~~~~~~~~~~~
>> kernel/time/hrtimer.c:944:1: warning: unused label 'set_timerfd' [-Wunused-label]
   set_timerfd:
   ^~~~~~~~~~~~
   kernel/time/hrtimer.c:147:20: warning: unused function 'is_migration_base' [-Wunused-function]
   static inline bool is_migration_base(struct hrtimer_clock_base *base)
                      ^
   kernel/time/hrtimer.c:650:19: warning: unused function 'hrtimer_hres_active' [-Wunused-function]
   static inline int hrtimer_hres_active(void)
                     ^
   kernel/time/hrtimer.c:881:13: warning: unused function 'need_reprogram_timer' [-Wunused-function]
   static bool need_reprogram_timer(struct hrtimer_cpu_base *cpu_base)
               ^
   kernel/time/hrtimer.c:1793:20: warning: unused function '__hrtimer_peek_ahead_timers' [-Wunused-function]
   static inline void __hrtimer_peek_ahead_timers(void) { }
                      ^
   9 warnings generated.


vim +/set_timerfd +944 kernel/time/hrtimer.c

   895	
   896	/*
   897	 * Clock realtime was set
   898	 *
   899	 * Change the offset of the realtime clock vs. the monotonic
   900	 * clock.
   901	 *
   902	 * We might have to reprogram the high resolution timer interrupt. On
   903	 * SMP we call the architecture specific code to retrigger _all_ high
   904	 * resolution timer interrupts. On UP we just disable interrupts and
   905	 * call the high resolution interrupt code.
   906	 */
   907	void clock_was_set(void)
   908	{
   909	#ifdef CONFIG_HIGH_RES_TIMERS
   910		cpumask_var_t mask;
   911		int cpu;
   912	
   913		if (!tick_nohz_full_enabled()) {
   914			/* Retrigger the CPU local events everywhere */
   915			on_each_cpu(retrigger_next_event, NULL, 1);
   916			goto set_timerfd;
   917		}
   918	
   919		if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
   920			on_each_cpu(retrigger_next_event, NULL, 1);
   921			goto set_timerfd;
   922		}
   923	
   924		/* Avoid interrupting nohz_full CPUs if possible */
   925		preempt_disable();
   926		for_each_online_cpu(cpu) {
   927			if (tick_nohz_full_cpu(cpu)) {
   928				unsigned long flags;
   929				struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
   930	
   931				raw_spin_lock_irqsave(&cpu_base->lock, flags);
   932				if (need_reprogram_timer(cpu_base))
   933					cpumask_set_cpu(cpu, mask);
   934				else
   935					hrtimer_update_base(cpu_base);
   936				raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
   937			}
   938		}
   939	
   940		smp_call_function_many(mask, retrigger_next_event, NULL, 1);
   941		preempt_enable();
   942		free_cpumask_var(mask);
   943	#endif
 > 944	set_timerfd:
   945		timerfd_clock_was_set();
   946	}
   947	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 27570 bytes --]