sched/headers: Reorganize, clean up and optimize kernel/sched/sched.h dependencies

Remove all headers, except the ones required to make this header
build standalone.

Also include stats.h in sched.h explicitly - dependencies already
require this.

Summary of the build speedup gained through the last ~15 scheduler build &
header dependency patches:

Cumulative scheduler (kernel/sched/) build time speedup on a
Linux distribution's config, which enables all scheduler features,
compared to the vanilla kernel:

  _____________________________________________________________________________
 |
 |  Vanilla kernel (v5.13-rc7):
 |_____________________________________________________________________________
 |
 |  Performance counter stats for 'make -j96 kernel/sched/' (3 runs):
 |
 |   126,975,564,374      instructions              #    1.45  insn per cycle           ( +-  0.00% )
 |    87,637,847,671      cycles                    #    3.959 GHz                      ( +-  0.30% )
 |         22,136.96 msec cpu-clock                 #    7.499 CPUs utilized            ( +-  0.29% )
 |
 |            2.9520 +- 0.0169 seconds time elapsed  ( +-  0.57% )
 |_____________________________________________________________________________
 |
 |  Patched kernel:
 |_____________________________________________________________________________
 |
 | Performance counter stats for 'make -j96 kernel/sched/' (3 runs):
 |
 |    50,420,496,914      instructions              #    1.47  insn per cycle           ( +-  0.00% )
 |    34,234,322,038      cycles                    #    3.946 GHz                      ( +-  0.31% )
 |          8,675.81 msec cpu-clock                 #    3.053 CPUs utilized            ( +-  0.45% )
 |
 |            2.8420 +- 0.0181 seconds time elapsed  ( +-  0.64% )
 |_____________________________________________________________________________

Summary:

  - CPU time used to build the scheduler dropped by -60.9%, a reduction
    from 22.1 clock-seconds to 8.7 clock-seconds.

  - Wall-clock time to build the scheduler dropped by -3.9%, a reduction
    from 2.95 seconds to 2.84 seconds.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

kernel/sched/build_policy.c

@@ -28,10 +28,6 @@
 #include <linux/tsacct_kern.h>
 #include <linux/vtime.h>
 
-#ifdef CONFIG_PARAVIRT
-# include <asm/paravirt.h>
-#endif
-
 #include <uapi/linux/sched/types.h>
 
 #include "sched.h"

kernel/sched/build_utility.c

@@ -44,13 +44,11 @@
 #include <linux/wait_api.h>
 #include <linux/workqueue_api.h>
 
-#ifdef CONFIG_PARAVIRT
-# include <asm/paravirt.h>
-#endif
-
 #include <uapi/linux/prctl.h>
 #include <uapi/linux/sched/types.h>
 
+#include <asm/switch_to.h>
+
 #include "sched.h"
 #include "sched-pelt.h"
 #include "stats.h"

kernel/sched/sched.h

@@ -5,99 +5,74 @@
 #ifndef _KERNEL_SCHED_SCHED_H
 #define _KERNEL_SCHED_SCHED_H
 
-#include <linux/sched.h>
-#include <linux/cpumask.h>
-#include <linux/ktime_api.h>
-#include <linux/cgroup_api.h>
-#include <linux/topology.h>
-#include <linux/prctl.h>
-#include <linux/ptrace_api.h>
-#include <linux/gfp_api.h>
-#include <linux/posix-timers.h>
-#include <linux/sched/clock.h>
-#include <linux/workqueue_api.h>
-#include <linux/tick.h>
-#include <linux/ktime_api.h>
-#include <linux/swait_api.h>
-#include <linux/hashtable_api.h>
-#include <linux/cpufreq.h>
-#include <linux/utsname.h>
-
-#include <asm/irq_regs.h>
-
 #include <linux/sched/affinity.h>
 #include <linux/sched/autogroup.h>
-#include <linux/sched/clock.h>
-#include <linux/sched/coredump.h>
 #include <linux/sched/cpufreq.h>
-#include <linux/sched/cputime.h>
 #include <linux/sched/deadline.h>
-#include <linux/sched/debug.h>
-#include <linux/sched/hotplug.h>
-#include <linux/sched/idle.h>
-#include <linux/sched/init.h>
-#include <linux/sched/isolation.h>
-#include <linux/sched/jobctl.h>
+#include <linux/sched.h>
 #include <linux/sched/loadavg.h>
 #include <linux/sched/mm.h>
-#include <linux/sched/nohz.h>
-#include <linux/sched/numa_balancing.h>
-#include <linux/sched/prio.h>
 #include <linux/sched/rseq_api.h>
-#include <linux/sched/rt.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/smt.h>
 #include <linux/sched/stat.h>
 #include <linux/sched/sysctl.h>
+#include <linux/sched/task_flags.h>
 #include <linux/sched/task.h>
-#include <linux/sched/task_stack.h>
-#include <linux/sched/thread_info_api.h>
 #include <linux/sched/topology.h>
-#include <linux/sched/user.h>
-#include <linux/sched/wake_q.h>
-#include <linux/sched/xacct.h>
 
-#include <uapi/linux/sched/types.h>
-
-#include <linux/binfmts.h>
-#include <linux/bitops.h>
-#include <linux/compat.h>
-#include <linux/context_tracking.h>
+#include <linux/atomic.h>
+#include <linux/bitmap.h>
+#include <linux/bug.h>
+#include <linux/capability.h>
+#include <linux/cgroup_api.h>
+#include <linux/cgroup.h>
 #include <linux/cpufreq.h>
-#include <linux/cpuidle.h>
-#include <linux/cpuset.h>
+#include <linux/cpumask_api.h>
 #include <linux/ctype.h>
-#include <linux/debugfs.h>
-#include <linux/delayacct.h>
-#include <linux/energy_model.h>
-#include <linux/init_task.h>
-#include <linux/kprobes.h>
+#include <linux/file.h>
+#include <linux/fs_api.h>
+#include <linux/hrtimer_api.h>
+#include <linux/interrupt.h>
+#include <linux/irq_work.h>
+#include <linux/jiffies.h>
+#include <linux/kref_api.h>
 #include <linux/kthread.h>
-#include <linux/membarrier.h>
-#include <linux/migrate.h>
-#include <linux/mmu_context.h>
-#include <linux/nmi.h>
+#include <linux/ktime_api.h>
+#include <linux/lockdep_api.h>
+#include <linux/lockdep.h>
+#include <linux/minmax.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mutex_api.h>
+#include <linux/plist.h>
+#include <linux/poll.h>
 #include <linux/proc_fs.h>
-#include <linux/prefetch.h>
 #include <linux/profile.h>
 #include <linux/psi.h>
-#include <linux/ratelimit.h>
-#include <linux/rcupdate_wait.h>
-#include <linux/security.h>
+#include <linux/rcupdate.h>
+#include <linux/seq_file.h>
+#include <linux/seqlock.h>
+#include <linux/softirq.h>
+#include <linux/spinlock_api.h>
+#include <linux/static_key.h>
 #include <linux/stop_machine.h>
-#include <linux/suspend.h>
-#include <linux/swait.h>
+#include <linux/syscalls_api.h>
 #include <linux/syscalls.h>
-#include <linux/task_work.h>
-#include <linux/tsacct_kern.h>
-#include <linux/hrtimer_api.h>
-
-#ifdef CONFIG_PARAVIRT
-# include <asm/paravirt.h>
-#endif
+#include <linux/tick.h>
+#include <linux/topology.h>
+#include <linux/types.h>
+#include <linux/u64_stats_sync_api.h>
+#include <linux/uaccess.h>
+#include <linux/wait_api.h>
+#include <linux/wait_bit.h>
+#include <linux/workqueue_api.h>
 
+#include <trace/events/power.h>
 #include <trace/events/sched.h>
 
+#include "../workqueue_internal.h"
+
 #ifdef CONFIG_CGROUP_SCHED
 #include <linux/cgroup.h>
 #include <linux/psi.h>
@@ -107,56 +82,20 @@
 # include <linux/static_key.h>
 #endif
 
+#ifdef CONFIG_PARAVIRT
+# include <asm/paravirt.h>
+# include <asm/paravirt_api_clock.h>
+#endif
+
 #include "cpupri.h"
 #include "cpudeadline.h"
 
 #ifdef CONFIG_SCHED_DEBUG
-# define SCHED_WARN_ON(x)	WARN_ONCE(x, #x)
+# define SCHED_WARN_ON(x)      WARN_ONCE(x, #x)
 #else
-# define SCHED_WARN_ON(x)	({ (void)(x), 0; })
+# define SCHED_WARN_ON(x)      ({ (void)(x), 0; })
 #endif
 
-#include <linux/bitmap.h>
-#include <linux/capability.h>
-#include <linux/cgroup.h>
-#include <linux/cpufreq.h>
-#include <linux/cpumask_api.h>
-#include <linux/ctype.h>
-#include <linux/file.h>
-#include <linux/hrtimer_api.h>
-#include <linux/interrupt.h>
-#include <linux/jiffies.h>
-#include <linux/kref_api.h>
-#include <linux/ktime_api.h>
-#include <linux/lockdep_api.h>
-#include <linux/module.h>
-#include <linux/mutex_api.h>
-#include <linux/poll.h>
-#include <linux/proc_fs.h>
-#include <linux/psi.h>
-#include <linux/sched/affinity.h>
-#include <linux/sched.h>
-#include <linux/sched/loadavg.h>
-#include <linux/sched/mm.h>
-#include <linux/sched/rseq_api.h>
-#include <linux/sched/signal.h>
-#include <linux/seq_file.h>
-#include <linux/seqlock.h>
-#include <linux/softirq.h>
-#include <linux/spinlock_api.h>
-#include <linux/syscalls_api.h>
-#include <linux/syscalls.h>
-#include <linux/topology.h>
-#include <linux/types.h>
-#include <linux/u64_stats_sync_api.h>
-#include <linux/uaccess.h>
-#include <linux/wait_api.h>
-#include <linux/workqueue_api.h>
-
-#include <trace/events/power.h>
-
-#include "../workqueue_internal.h"
-
 struct rq;
 struct cpuidle_state;
 
@@ -1925,6 +1864,8 @@ extern void flush_smp_call_function_from_idle(void);
 static inline void flush_smp_call_function_from_idle(void) { }
 #endif
 
+#include "stats.h"
+
 #if defined(CONFIG_SCHED_CORE) && defined(CONFIG_SCHEDSTATS)
 
 extern void __sched_core_account_forceidle(struct rq *rq);

kernel/sched/stats.h

@@ -2,8 +2,6 @@
 #ifndef _KERNEL_STATS_H
 #define _KERNEL_STATS_H
 
-#include "sched.h"
-
 #ifdef CONFIG_SCHEDSTATS
 
 extern struct static_key_false sched_schedstats;