Re: [PATCH 1/2] sched/fair: keep load_avg and load_sum synced

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

[-- Attachment #1: Type: text/plain, Size: 6740 bytes --]

Hi Vincent,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on tip/master linux/master linus/master v5.13-rc3 next-20210527]
[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/Vincent-Guittot/schd-fair-fix-stalled-cfs_rq-tg_load_avg_contrib/20210527-203115
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git a8ea6fc9b089156d9230bfeef964dd9be101a4a9
config: s390-randconfig-c024-20210527 (attached as .config)
compiler: s390-linux-gcc (GCC) 9.3.0
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/725167b3ef5a796c98add27cb21e543c7b72cf0e
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Vincent-Guittot/schd-fair-fix-stalled-cfs_rq-tg_load_avg_contrib/20210527-203115
        git checkout 725167b3ef5a796c98add27cb21e543c7b72cf0e
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=s390 

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/sched/fair.c: In function 'update_tg_cfs_load':
>> kernel/sched/fair.c:3459:6: warning: variable 'delta_sum' set but not used [-Wunused-but-set-variable]
    3459 |  s64 delta_sum;
         |      ^~~~~~~~~


vim +/delta_sum +3459 kernel/sched/fair.c

9f68395333ad7f Vincent Guittot 2020-02-24  3452  
09a43ace1f986b Vincent Guittot 2016-11-08  3453  static inline void
0dacee1bfa70e1 Vincent Guittot 2020-02-24  3454  update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
09a43ace1f986b Vincent Guittot 2016-11-08  3455  {
a4c3c04974d648 Vincent Guittot 2017-11-16  3456  	long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;
0dacee1bfa70e1 Vincent Guittot 2020-02-24  3457  	unsigned long load_avg;
0dacee1bfa70e1 Vincent Guittot 2020-02-24  3458  	u64 load_sum = 0;
a4c3c04974d648 Vincent Guittot 2017-11-16 @3459  	s64 delta_sum;
95d685935a2edf Vincent Guittot 2020-05-06  3460  	u32 divider;
09a43ace1f986b Vincent Guittot 2016-11-08  3461  
0e2d2aaaae52c2 Peter Zijlstra  2017-05-08  3462  	if (!runnable_sum)
0e2d2aaaae52c2 Peter Zijlstra  2017-05-08  3463  		return;
09a43ace1f986b Vincent Guittot 2016-11-08  3464  
0e2d2aaaae52c2 Peter Zijlstra  2017-05-08  3465  	gcfs_rq->prop_runnable_sum = 0;
09a43ace1f986b Vincent Guittot 2016-11-08  3466  
95d685935a2edf Vincent Guittot 2020-05-06  3467  	/*
95d685935a2edf Vincent Guittot 2020-05-06  3468  	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
95d685935a2edf Vincent Guittot 2020-05-06  3469  	 * See ___update_load_avg() for details.
95d685935a2edf Vincent Guittot 2020-05-06  3470  	 */
87e867b4269f29 Vincent Guittot 2020-06-12  3471  	divider = get_pelt_divider(&cfs_rq->avg);
95d685935a2edf Vincent Guittot 2020-05-06  3472  
a4c3c04974d648 Vincent Guittot 2017-11-16  3473  	if (runnable_sum >= 0) {
a4c3c04974d648 Vincent Guittot 2017-11-16  3474  		/*
a4c3c04974d648 Vincent Guittot 2017-11-16  3475  		 * Add runnable; clip at LOAD_AVG_MAX. Reflects that until
a4c3c04974d648 Vincent Guittot 2017-11-16  3476  		 * the CPU is saturated running == runnable.
a4c3c04974d648 Vincent Guittot 2017-11-16  3477  		 */
a4c3c04974d648 Vincent Guittot 2017-11-16  3478  		runnable_sum += se->avg.load_sum;
95d685935a2edf Vincent Guittot 2020-05-06  3479  		runnable_sum = min_t(long, runnable_sum, divider);
a4c3c04974d648 Vincent Guittot 2017-11-16  3480  	} else {
a4c3c04974d648 Vincent Guittot 2017-11-16  3481  		/*
a4c3c04974d648 Vincent Guittot 2017-11-16  3482  		 * Estimate the new unweighted runnable_sum of the gcfs_rq by
a4c3c04974d648 Vincent Guittot 2017-11-16  3483  		 * assuming all tasks are equally runnable.
a4c3c04974d648 Vincent Guittot 2017-11-16  3484  		 */
a4c3c04974d648 Vincent Guittot 2017-11-16  3485  		if (scale_load_down(gcfs_rq->load.weight)) {
a4c3c04974d648 Vincent Guittot 2017-11-16  3486  			load_sum = div_s64(gcfs_rq->avg.load_sum,
a4c3c04974d648 Vincent Guittot 2017-11-16  3487  				scale_load_down(gcfs_rq->load.weight));
a4c3c04974d648 Vincent Guittot 2017-11-16  3488  		}
a4c3c04974d648 Vincent Guittot 2017-11-16  3489  
a4c3c04974d648 Vincent Guittot 2017-11-16  3490  		/* But make sure to not inflate se's runnable */
a4c3c04974d648 Vincent Guittot 2017-11-16  3491  		runnable_sum = min(se->avg.load_sum, load_sum);
a4c3c04974d648 Vincent Guittot 2017-11-16  3492  	}
a4c3c04974d648 Vincent Guittot 2017-11-16  3493  
a4c3c04974d648 Vincent Guittot 2017-11-16  3494  	/*
a4c3c04974d648 Vincent Guittot 2017-11-16  3495  	 * runnable_sum can't be lower than running_sum
23127296889fe8 Vincent Guittot 2019-01-23  3496  	 * Rescale running sum to be in the same range as runnable sum
23127296889fe8 Vincent Guittot 2019-01-23  3497  	 * running_sum is in [0 : LOAD_AVG_MAX <<  SCHED_CAPACITY_SHIFT]
23127296889fe8 Vincent Guittot 2019-01-23  3498  	 * runnable_sum is in [0 : LOAD_AVG_MAX]
a4c3c04974d648 Vincent Guittot 2017-11-16  3499  	 */
23127296889fe8 Vincent Guittot 2019-01-23  3500  	running_sum = se->avg.util_sum >> SCHED_CAPACITY_SHIFT;
a4c3c04974d648 Vincent Guittot 2017-11-16  3501  	runnable_sum = max(runnable_sum, running_sum);
a4c3c04974d648 Vincent Guittot 2017-11-16  3502  
0e2d2aaaae52c2 Peter Zijlstra  2017-05-08  3503  	load_sum = (s64)se_weight(se) * runnable_sum;
95d685935a2edf Vincent Guittot 2020-05-06  3504  	load_avg = div_s64(load_sum, divider);
09a43ace1f986b Vincent Guittot 2016-11-08  3505  
a4c3c04974d648 Vincent Guittot 2017-11-16  3506  	delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;
a4c3c04974d648 Vincent Guittot 2017-11-16  3507  	delta_avg = load_avg - se->avg.load_avg;
09a43ace1f986b Vincent Guittot 2016-11-08  3508  
a4c3c04974d648 Vincent Guittot 2017-11-16  3509  	se->avg.load_sum = runnable_sum;
a4c3c04974d648 Vincent Guittot 2017-11-16  3510  	se->avg.load_avg = load_avg;
a4c3c04974d648 Vincent Guittot 2017-11-16  3511  	add_positive(&cfs_rq->avg.load_avg, delta_avg);
725167b3ef5a79 Vincent Guittot 2021-05-27  3512  	cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * divider;
725167b3ef5a79 Vincent Guittot 2021-05-27  3513  

---
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: 16483 bytes --]