Hi Stephane, Thank you for the patch! Yet something to improve: [auto build test ERROR on tip/perf/core] [also build test ERROR on tip/x86/core v5.16-rc5] [cannot apply to rafael-pm/linux-next] [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/Stephane-Eranian/perf-x86-amd-Ad... base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git a9f4a6e92b3b319296fb078da2615f618f6cd80c config: i386-randconfig-a013-20211210 (https://download.01.org/0day-ci/archive/20211213/202112131356.nvv2mpcK-lk...) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 097a1cb1d5ebb3a0ec4bcaed8ba3ff6a8e33c00a) 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 # https://github.com/0day-ci/linux/commit/9d928356688ed9c42e01fed16e59c1d6e... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Stephane-Eranian/perf-x86-amd-Add-AMD-Fam19h-Branch-Sampling-support/20211211-050541 git checkout 9d928356688ed9c42e01fed16e59c1d6eda16647 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/acpi/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): perf_lopwr_cb(true); ^ 1 error generated. vim +/perf_lopwr_cb +168 drivers/acpi/acpi_pad.c 135 136 static unsigned int idle_pct = 5; /* percentage */ 137 static unsigned int round_robin_time = 1; /* second */ 138 static int power_saving_thread(void *data) 139 { 140 int do_sleep; 141 unsigned int tsk_index = (unsigned long)data; 142 u64 last_jiffies = 0; 143 144 sched_set_fifo_low(current); 145 146 while (!kthread_should_stop()) { 147 unsigned long expire_time; 148 149 /* round robin to cpus */ 150 expire_time = last_jiffies + round_robin_time * HZ; 151 if (time_before(expire_time, jiffies)) { 152 last_jiffies = jiffies; 153 round_robin_cpu(tsk_index); 154 } 155 156 do_sleep = 0; 157 158 expire_time = jiffies + HZ * (100 - idle_pct) / 100; 159 160 while (!need_resched()) { 161 if (tsc_detected_unstable && !tsc_marked_unstable) { 162 /* TSC could halt in idle, so notify users */ 163 mark_tsc_unstable("TSC halts in idle"); 164 tsc_marked_unstable = 1; 165 } 166 local_irq_disable(); 167 169 170 tick_broadcast_enable(); 171 tick_broadcast_enter(); 172 stop_critical_timings(); 173 174 mwait_idle_with_hints(power_saving_mwait_eax, 1); 175 176 start_critical_timings(); 177 tick_broadcast_exit(); 178 179 perf_lopwr_cb(false); 180 181 local_irq_enable(); 182 183 if (time_before(expire_time, jiffies)) { 184 do_sleep = 1; 185 break; 186 } 187 } 188 189 /* 190 * current sched_rt has threshold for rt task running time. 191 * When a rt task uses 95% CPU time, the rt thread will be 192 * scheduled out for 5% CPU time to not starve other tasks. But 193 * the mechanism only works when all CPUs have RT task running, 194 * as if one CPU hasn't RT task, RT task from other CPUs will 195 * borrow CPU time from this CPU and cause RT task use > 95% 196 * CPU time. To make 'avoid starvation' work, takes a nap here. 197 */ 198 if (unlikely(do_sleep)) 199 schedule_timeout_killable(HZ * idle_pct / 100); 200 201 /* If an external event has set the need_resched flag, then 202 * we need to deal with it, or this loop will continue to 203 * spin without calling __mwait(). 204 */ 205 if (unlikely(need_resched())) 206 schedule(); 207 } 208 209 exit_round_robin(tsk_index); 210 return 0; 211 } 212 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org