Hi, kernel test robot noticed the following build warnings: [auto build test WARNING on vfs-idmapping/for-next] [also build test WARNING on linus/master v6.3-rc7] [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/wenyang-linux-foxmail-com/eventfd-support-delayed-wakeup-for-non-semaphore-eventfd-to-reduce-cpu-utilization/20230416-193353 base: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping.git for-next patch link: https://lore.kernel.org/r/tencent_AF886EF226FD9F39D28FE4D9A94A95FA2605%40qq.com patch subject: [PATCH] eventfd: support delayed wakeup for non-semaphore eventfd to reduce cpu utilization reproduce: # https://github.com/intel-lab-lkp/linux/commit/ea9214e265bae223a795f144d6ddcac65e8e2084 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review wenyang-linux-foxmail-com/eventfd-support-delayed-wakeup-for-non-semaphore-eventfd-to-reduce-cpu-utilization/20230416-193353 git checkout ea9214e265bae223a795f144d6ddcac65e8e2084 make menuconfig # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS make htmldocs If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Link: https://lore.kernel.org/oe-kbuild-all/202304172058.piI49JCE-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): >> Documentation/admin-guide/sysctl/fs.rst:74: WARNING: Title underline too short. vim +74 Documentation/admin-guide/sysctl/fs.rst 72 73 eventfd_wakeup_delay_msec > 74 ------------------ 75 Frequent writing of an eventfd can also lead to frequent wakeup of the peer 76 read process, resulting in significant cpu overhead. 77 How ever for the NON SEMAPHORE eventfd, if it's counter has a nonzero value, 78 then a read(2) returns 8 bytes containing that value, and the counter's value 79 is reset to zero. 80 So it coule be optimized as follows: N event_writes vs ONE event_read. 81 By adding a configurable delay after eventfd_write, these unnecessary wakeup 82 operations are avoided. 83 The max value is 100 ms. 84 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests
