Re: [PATCH] sched/cputime: Mitigate performance regression in times()/clock_gettime()

From: kbuild test robot
Date: Tue Jul 26 2016 - 10:44:35 EST


[auto build test ERROR on tip/sched/core]
[also build test ERROR on v4.7 next-20160726]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

config: mips-allyesconfig (attached as .config)
compiler: mips-linux-gnu-gcc (Debian 5.4.0-6) 5.4.0 20160609
wget -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=mips

All errors (new ones prefixed by >>):

kernel/sched/core.c: In function 'task_sched_runtime':
>> kernel/sched/core.c:3009:3: error: implicit declaration of function 'prefetch' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[2]: *** [kernel/sched/core.o] Error 1
make[2]: Target '__build' not remade because of errors.
make[1]: *** [kernel/sched/] Error 2

vim +/prefetch +3009 kernel/sched/core.c

3003 * Must be ->curr _and_ ->on_rq. If dequeued, we would
3004 * project cycles that may never be accounted to this
3005 * thread, breaking clock_gettime().
3006 */
3007 if (task_current(rq, p) && task_on_rq_queued(p)) {
3008 #if defined(CONFIG_FAIR_GROUP_SCHED)
> 3009 prefetch((&p->se)->cfs_rq->curr);
3010 prefetch(&(&p->se)->cfs_rq->curr->exec_start);
3011 #endif
3012 update_rq_clock(rq);

0-DAY kernel test infrastructure Open Source Technology Center Intel Corporation

Attachment: .config.gz
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