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X-CSE-ConnectionGUID: dpzLQHUgQkOeilmVDPYUGw== X-CSE-MsgGUID: kmNxUw4eS3SrhwNAd6elNw== X-IronPort-AV: E=McAfee;i="6800,10657,11483"; a="53117923" X-IronPort-AV: E=Sophos;i="6.16,284,1744095600"; d="scan'208";a="53117923" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jul 2025 09:02:45 -0700 X-CSE-ConnectionGUID: itwYFqXiTEqwrPVag3Qfzw== X-CSE-MsgGUID: Bg1RtVG/RPuhzHyjrcaYag== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,284,1744095600"; d="scan'208";a="158679754" Received: from lkp-server01.sh.intel.com (HELO 0b2900756c14) ([10.239.97.150]) by fmviesa005.fm.intel.com with ESMTP; 03 Jul 2025 09:02:42 -0700 Received: from kbuild by 0b2900756c14 with local (Exim 4.96) (envelope-from ) id 1uXMOW-0002ky-0f; Thu, 03 Jul 2025 16:02:40 +0000 Date: Fri, 4 Jul 2025 00:02:23 +0800 From: kernel test robot To: Christoph Lameter via B4 Relay , Anna-Maria Behnsen , Frederic Weisbecker , Ingo Molnar , Thomas Gleixner Cc: oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, sh@gentwo.org, Darren Hart , "Christoph Lameter (Ampere)" Subject: Re: [PATCH] Skew tick for systems with a large number of processors Message-ID: <202507032322.5jzirIYw-lkp@intel.com> References: <20250702-tick_skew-v1-1-ff8d73035b02@gentwo.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250702-tick_skew-v1-1-ff8d73035b02@gentwo.org> Hi Christoph, kernel test robot noticed the following build errors: [auto build test ERROR on 66701750d5565c574af42bef0b789ce0203e3071] url: https://github.com/intel-lab-lkp/linux/commits/Christoph-Lameter-via-B4-Relay/Skew-tick-for-systems-with-a-large-number-of-processors/20250703-034357 base: 66701750d5565c574af42bef0b789ce0203e3071 patch link: https://lore.kernel.org/r/20250702-tick_skew-v1-1-ff8d73035b02%40gentwo.org patch subject: [PATCH] Skew tick for systems with a large number of processors config: arc-randconfig-002-20250703 (https://download.01.org/0day-ci/archive/20250703/202507032322.5jzirIYw-lkp@intel.com/config) compiler: arc-linux-gcc (GCC) 12.4.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250703/202507032322.5jzirIYw-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 | Closes: https://lore.kernel.org/oe-kbuild-all/202507032322.5jzirIYw-lkp@intel.com/ All errors (new ones prefixed by >>): kernel/time/tick-sched.c: In function 'tick_setup_sched_timer': >> kernel/time/tick-sched.c:1577:44: error: 'CONFIG_TICK_SKEW_LIMIT' undeclared (first use in this function); did you mean 'CONFIG_TICK_ONESHOT'? 1577 | if (num_possible_cpus() >= CONFIG_TICK_SKEW_LIMIT) { | ^~~~~~~~~~~~~~~~~~~~~~ | CONFIG_TICK_ONESHOT kernel/time/tick-sched.c:1577:44: note: each undeclared identifier is reported only once for each function it appears in vim +1577 kernel/time/tick-sched.c 1566 1567 /** 1568 * tick_setup_sched_timer - setup the tick emulation timer 1569 * @hrtimer: whether to use the hrtimer or not 1570 */ 1571 void tick_setup_sched_timer(bool hrtimer) 1572 { 1573 struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); 1574 1575 /* Figure out if we should skew the tick */ 1576 if (sched_skew_tick < 0) { > 1577 if (num_possible_cpus() >= CONFIG_TICK_SKEW_LIMIT) { 1578 sched_skew_tick = 1; 1579 pr_info("Tick skewed mode enabled. Possible cpus %u > %u\n", 1580 num_possible_cpus(), CONFIG_TICK_SKEW_LIMIT); 1581 } else 1582 sched_skew_tick = 0; 1583 } 1584 1585 /* Emulate tick processing via per-CPU hrtimers: */ 1586 hrtimer_setup(&ts->sched_timer, tick_nohz_handler, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD); 1587 1588 if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && hrtimer) 1589 tick_sched_flag_set(ts, TS_FLAG_HIGHRES); 1590 1591 /* Get the next period (per-CPU) */ 1592 hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); 1593 1594 /* Offset the tick to avert 'jiffies_lock' contention. */ 1595 if (sched_skew_tick) { 1596 u64 offset = TICK_NSEC >> 1; 1597 do_div(offset, num_possible_cpus()); 1598 offset *= smp_processor_id(); 1599 hrtimer_add_expires_ns(&ts->sched_timer, offset); 1600 } else 1601 pr_info("Tick operating in synchronized mode.\n"); 1602 1603 1604 hrtimer_forward_now(&ts->sched_timer, TICK_NSEC); 1605 if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && hrtimer) 1606 hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED_HARD); 1607 else 1608 tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); 1609 tick_nohz_activate(ts); 1610 } 1611 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki