Re: [RFC v6 2/5] sched/core: Update turbo_sched count only when required

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

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Hi Parth,

[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on tip/sched/core]
[also build test WARNING on powerpc/next tip/auto-latest linux/master linus/master v5.5-rc7 next-20200123]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Parth-Shah/TurboSched-A-scheduler-for-sustaining-Turbo-Frequencies-for-longer-durations/20200124-041428
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git afa70d941f663c69c9a64ec1021bbcfa82f0e54a
config: i386-randconfig-c002-20200124 (attached as .config)
compiler: gcc-7 (Debian 7.5.0-3) 7.5.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from arch/x86/include/asm/current.h:5:0,
                    from include/linux/sched.h:12,
                    from kernel/sched/sched.h:5,
                    from kernel/sched/core.c:9:
   kernel/sched/core.c: In function 'finish_task_switch':
   kernel/sched/sched.h:2484:45: error: 'struct task_struct' has no member named 'latency_nice'; did you mean 'latency_record'?
    #define is_bg_task(p)  (bgtask_latency((p)->latency_nice))
                                                ^
   include/linux/compiler.h:33:34: note: in definition of macro '__branch_check__'
       ______r = __builtin_expect(!!(x), expect); \
                                     ^
>> kernel/sched/core.c:3272:7: note: in expansion of macro 'unlikely'
      if (unlikely(is_bg_task(prev)))
          ^~~~~~~~
   kernel/sched/sched.h:2484:25: note: in expansion of macro 'bgtask_latency'
    #define is_bg_task(p)  (bgtask_latency((p)->latency_nice))
                            ^~~~~~~~~~~~~~
   kernel/sched/core.c:3272:16: note: in expansion of macro 'is_bg_task'
      if (unlikely(is_bg_task(prev)))
                   ^~~~~~~~~~
   kernel/sched/sched.h:2483:39: error: 'MAX_LATENCY_NICE' undeclared (first use in this function); did you mean 'MAX_OPTINSN_SIZE'?
    #define bgtask_latency(lat) ((lat) == MAX_LATENCY_NICE)
                                          ^
   include/linux/compiler.h:33:34: note: in definition of macro '__branch_check__'
       ______r = __builtin_expect(!!(x), expect); \
                                     ^
>> kernel/sched/core.c:3272:7: note: in expansion of macro 'unlikely'
      if (unlikely(is_bg_task(prev)))
          ^~~~~~~~
   kernel/sched/sched.h:2484:25: note: in expansion of macro 'bgtask_latency'
    #define is_bg_task(p)  (bgtask_latency((p)->latency_nice))
                            ^~~~~~~~~~~~~~
   kernel/sched/core.c:3272:16: note: in expansion of macro 'is_bg_task'
      if (unlikely(is_bg_task(prev)))
                   ^~~~~~~~~~
   kernel/sched/sched.h:2483:39: note: each undeclared identifier is reported only once for each function it appears in
    #define bgtask_latency(lat) ((lat) == MAX_LATENCY_NICE)
                                          ^
   include/linux/compiler.h:33:34: note: in definition of macro '__branch_check__'
       ______r = __builtin_expect(!!(x), expect); \
                                     ^
>> kernel/sched/core.c:3272:7: note: in expansion of macro 'unlikely'
      if (unlikely(is_bg_task(prev)))
          ^~~~~~~~
   kernel/sched/sched.h:2484:25: note: in expansion of macro 'bgtask_latency'
    #define is_bg_task(p)  (bgtask_latency((p)->latency_nice))
                            ^~~~~~~~~~~~~~
   kernel/sched/core.c:3272:16: note: in expansion of macro 'is_bg_task'
      if (unlikely(is_bg_task(prev)))
                   ^~~~~~~~~~
   kernel/sched/sched.h:2484:45: error: 'struct task_struct' has no member named 'latency_nice'; did you mean 'latency_record'?
    #define is_bg_task(p)  (bgtask_latency((p)->latency_nice))
                                                ^
   include/linux/compiler.h:35:19: note: in definition of macro '__branch_check__'
              expect, is_constant); \
                      ^~~~~~~~~~~
>> kernel/sched/core.c:3272:7: note: in expansion of macro 'unlikely'
      if (unlikely(is_bg_task(prev)))
          ^~~~~~~~
   kernel/sched/sched.h:2484:25: note: in expansion of macro 'bgtask_latency'
    #define is_bg_task(p)  (bgtask_latency((p)->latency_nice))
                            ^~~~~~~~~~~~~~
   kernel/sched/core.c:3272:16: note: in expansion of macro 'is_bg_task'
      if (unlikely(is_bg_task(prev)))
                   ^~~~~~~~~~
   In file included from kernel/sched/core.c:9:0:
   kernel/sched/core.c: In function '__sched_setscheduler':
   kernel/sched/core.c:4801:44: error: 'const struct sched_attr' has no member named 'sched_latency_nice'; did you mean 'sched_nice'?
     bool attr_leniency = bgtask_latency(attr->sched_latency_nice);
                                               ^
   kernel/sched/sched.h:2483:31: note: in definition of macro 'bgtask_latency'
    #define bgtask_latency(lat) ((lat) == MAX_LATENCY_NICE)
                                  ^~~
   kernel/sched/sched.h:2483:39: error: 'MAX_LATENCY_NICE' undeclared (first use in this function); did you mean 'MAX_OPTINSN_SIZE'?
    #define bgtask_latency(lat) ((lat) == MAX_LATENCY_NICE)
                                          ^
   kernel/sched/core.c:4801:23: note: in expansion of macro 'bgtask_latency'
     bool attr_leniency = bgtask_latency(attr->sched_latency_nice);
                          ^~~~~~~~~~~~~~
   kernel/sched/sched.h:2484:45: error: 'struct task_struct' has no member named 'latency_nice'; did you mean 'latency_record'?
    #define is_bg_task(p)  (bgtask_latency((p)->latency_nice))
                                                ^
   kernel/sched/sched.h:2483:31: note: in definition of macro 'bgtask_latency'
    #define bgtask_latency(lat) ((lat) == MAX_LATENCY_NICE)
                                  ^~~
   kernel/sched/core.c:5018:6: note: in expansion of macro 'is_bg_task'
     if (is_bg_task(p) != attr_leniency)
         ^~~~~~~~~~

vim +/unlikely +3272 kernel/sched/core.c

  3190	
  3191	/**
  3192	 * finish_task_switch - clean up after a task-switch
  3193	 * @prev: the thread we just switched away from.
  3194	 *
  3195	 * finish_task_switch must be called after the context switch, paired
  3196	 * with a prepare_task_switch call before the context switch.
  3197	 * finish_task_switch will reconcile locking set up by prepare_task_switch,
  3198	 * and do any other architecture-specific cleanup actions.
  3199	 *
  3200	 * Note that we may have delayed dropping an mm in context_switch(). If
  3201	 * so, we finish that here outside of the runqueue lock. (Doing it
  3202	 * with the lock held can cause deadlocks; see schedule() for
  3203	 * details.)
  3204	 *
  3205	 * The context switch have flipped the stack from under us and restored the
  3206	 * local variables which were saved when this task called schedule() in the
  3207	 * past. prev == current is still correct but we need to recalculate this_rq
  3208	 * because prev may have moved to another CPU.
  3209	 */
  3210	static struct rq *finish_task_switch(struct task_struct *prev)
  3211		__releases(rq->lock)
  3212	{
  3213		struct rq *rq = this_rq();
  3214		struct mm_struct *mm = rq->prev_mm;
  3215		long prev_state;
  3216	
  3217		/*
  3218		 * The previous task will have left us with a preempt_count of 2
  3219		 * because it left us after:
  3220		 *
  3221		 *	schedule()
  3222		 *	  preempt_disable();			// 1
  3223		 *	  __schedule()
  3224		 *	    raw_spin_lock_irq(&rq->lock)	// 2
  3225		 *
  3226		 * Also, see FORK_PREEMPT_COUNT.
  3227		 */
  3228		if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
  3229			      "corrupted preempt_count: %s/%d/0x%x\n",
  3230			      current->comm, current->pid, preempt_count()))
  3231			preempt_count_set(FORK_PREEMPT_COUNT);
  3232	
  3233		rq->prev_mm = NULL;
  3234	
  3235		/*
  3236		 * A task struct has one reference for the use as "current".
  3237		 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
  3238		 * schedule one last time. The schedule call will never return, and
  3239		 * the scheduled task must drop that reference.
  3240		 *
  3241		 * We must observe prev->state before clearing prev->on_cpu (in
  3242		 * finish_task), otherwise a concurrent wakeup can get prev
  3243		 * running on another CPU and we could rave with its RUNNING -> DEAD
  3244		 * transition, resulting in a double drop.
  3245		 */
  3246		prev_state = prev->state;
  3247		vtime_task_switch(prev);
  3248		perf_event_task_sched_in(prev, current);
  3249		finish_task(prev);
  3250		finish_lock_switch(rq);
  3251		finish_arch_post_lock_switch();
  3252		kcov_finish_switch(current);
  3253	
  3254		fire_sched_in_preempt_notifiers(current);
  3255		/*
  3256		 * When switching through a kernel thread, the loop in
  3257		 * membarrier_{private,global}_expedited() may have observed that
  3258		 * kernel thread and not issued an IPI. It is therefore possible to
  3259		 * schedule between user->kernel->user threads without passing though
  3260		 * switch_mm(). Membarrier requires a barrier after storing to
  3261		 * rq->curr, before returning to userspace, so provide them here:
  3262		 *
  3263		 * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly
  3264		 *   provided by mmdrop(),
  3265		 * - a sync_core for SYNC_CORE.
  3266		 */
  3267		if (mm) {
  3268			membarrier_mm_sync_core_before_usermode(mm);
  3269			mmdrop(mm);
  3270		}
  3271		if (unlikely(prev_state == TASK_DEAD)) {
> 3272			if (unlikely(is_bg_task(prev)))
  3273				turbo_sched_put();
  3274	
  3275			if (prev->sched_class->task_dead)
  3276				prev->sched_class->task_dead(prev);
  3277	
  3278			/*
  3279			 * Remove function-return probe instances associated with this
  3280			 * task and put them back on the free list.
  3281			 */
  3282			kprobe_flush_task(prev);
  3283	
  3284			/* Task is done with its stack. */
  3285			put_task_stack(prev);
  3286	
  3287			put_task_struct_rcu_user(prev);
  3288		}
  3289	
  3290		tick_nohz_task_switch();
  3291		return rq;
  3292	}
  3293	

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