[patch] sched-2.5.29-B1

[patch] sched-2.5.29-B1

[Ingo Molnar]

the attached patch is a comment update of sched.c and it also does a small
cleanup in migration_thread().

 sched.c |  248 ++++++++++++++++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 202 insertions(+), 46 deletions(-)

	Ingo

--- linux/kernel/sched.c.orig	Sun Jul 28 10:13:00 2002
+++ linux/kernel/sched.c	Sun Jul 28 11:54:34 2002
@@ -111,9 +111,9 @@
  * BASE_TIMESLICE scales user-nice values [ -20 ... 19 ]
  * to time slice values.
  *
- * The higher a process's priority, the bigger timeslices
+ * The higher a thread's priority, the bigger timeslices
  * it gets during one round of execution. But even the lowest
- * priority process gets MIN_TIMESLICE worth of execution time.
+ * priority thread gets MIN_TIMESLICE worth of execution time.
  *
  * task_timeslice() is the interface that is used by the scheduler.
  */
@@ -144,7 +144,7 @@
  * This is the main, per-CPU runqueue data structure.
  *
  * Locking rule: those places that want to lock multiple runqueues
- * (such as the load balancing or the process migration code), lock
+ * (such as the load balancing or the thread migration code), lock
  * acquire operations must be ordered by ascending &runqueue.
  */
 struct runqueue {
@@ -241,21 +241,24 @@
 	p->array = array;
 }
 
+/*
+ * effective_prio - return the priority that is based on the static
+ * priority but is modified by bonuses/penalties.
+ *
+ * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
+ * into the -5 ... 0 ... +5 bonus/penalty range.
+ *
+ * We use 25% of the full 0...39 priority range so that:
+ *
+ * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
+ * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
+ *
+ * Both properties are important to certain workloads.
+ */
 static inline int effective_prio(task_t *p)
 {
 	int bonus, prio;
 
-	/*
-	 * Here we scale the actual sleep average [0 .... MAX_SLEEP_AVG]
-	 * into the -5 ... 0 ... +5 bonus/penalty range.
-	 *
-	 * We use 25% of the full 0...39 priority range so that:
-	 *
-	 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
-	 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
-	 *
-	 * Both properties are important to certain workloads.
-	 */
 	bonus = MAX_USER_PRIO*PRIO_BONUS_RATIO*p->sleep_avg/MAX_SLEEP_AVG/100 -
 			MAX_USER_PRIO*PRIO_BONUS_RATIO/100/2;
 
@@ -267,6 +270,12 @@
 	return prio;
 }
 
+/*
+ * activate_task - move a task to the runqueue.
+
+ * Also update all the scheduling statistics stuff. (sleep average
+ * calculation, priority modifiers, etc.)
+ */
 static inline void activate_task(task_t *p, runqueue_t *rq)
 {
 	unsigned long sleep_time = jiffies - p->sleep_timestamp;
@@ -289,6 +298,9 @@
 	rq->nr_running++;
 }
 
+/*
+ * deactivate_task - remove a task from the runqueue.
+ */
 static inline void deactivate_task(struct task_struct *p, runqueue_t *rq)
 {
 	rq->nr_running--;
@@ -298,6 +310,13 @@
 	p->array = NULL;
 }
 
+/*
+ * resched_task - mark a task 'to be rescheduled now'.
+ *
+ * On UP this means the setting of the need_resched flag, on SMP it
+ * might also involve a cross-CPU call to trigger the scheduler on
+ * the target CPU.
+ */
 static inline void resched_task(task_t *p)
 {
 #ifdef CONFIG_SMP
@@ -320,8 +339,10 @@
 #ifdef CONFIG_SMP
 
 /*
- * Wait for a process to unschedule. This is used by the exit() and
- * ptrace() code.
+ * wait_task_inactive - wait for a thread to unschedule.
+ *
+ * The caller must ensure that the task *will* unschedule sometime soon,
+ * else this function might spin for a *long* time.
  */
 void wait_task_inactive(task_t * p)
 {
@@ -353,9 +374,10 @@
 #endif
 
 /*
- * Kick the remote CPU if the task is running currently,
- * this code is used by the signal code to signal tasks
- * which are in user-mode as quickly as possible.
+ * kick_if_running - kick the remote CPU if the task is running currently.
+ *
+ * This code is used by the signal code to signal tasks
+ * which are in user-mode, as quickly as possible.
  *
  * (Note that we do this lockless - if the task does anything
  * while the message is in flight then it will notice the
@@ -367,13 +389,16 @@
 		resched_task(p);
 }
 
-/*
- * Wake up a process. Put it on the run-queue if it's not
- * already there.  The "current" process is always on the
- * run-queue (except when the actual re-schedule is in
- * progress), and as such you're allowed to do the simpler
- * "current->state = TASK_RUNNING" to mark yourself runnable
- * without the overhead of this.
+/***
+ * try_to_wake_up - wake up a thread
+ * @p: the to-be-woken-up thread
+ * @sync: do a synchronous wakeup?
+ *
+ * Put it on the run-queue if it's not already there. The "current"
+ * thread is always on the run-queue (except when the actual
+ * re-schedule is in progress), and as such you're allowed to do
+ * the simpler "current->state = TASK_RUNNING" to mark yourself
+ * runnable without the overhead of this.
  *
  * returns failure only if the task is already active.
  */
@@ -419,6 +444,12 @@
 	return try_to_wake_up(p, 0);
 }
 
+/*
+ * wake_up_forked_process - wake up a freshly forked process.
+ *
+ * This function will do some initial scheduler statistics housekeeping
+ * that must be done for every newly created process.
+ */
 void wake_up_forked_process(task_t * p)
 {
 	runqueue_t *rq = this_rq_lock();
@@ -443,7 +474,7 @@
 /*
  * Potentially available exiting-child timeslices are
  * retrieved here - this way the parent does not get
- * penalized for creating too many processes.
+ * penalized for creating too many threads.
  *
  * (this cannot be used to 'generate' timeslices
  * artificially, because any timeslice recovered here
@@ -467,6 +498,10 @@
 			p->sleep_avg) / (EXIT_WEIGHT + 1);
 }
 
+/**
+ * schedule_tail - first thing a freshly forked thread must call.
+ * @prev: the thread we just switched away from.
+ */
 #if CONFIG_SMP || CONFIG_PREEMPT
 asmlinkage void schedule_tail(task_t *prev)
 {
@@ -474,6 +509,10 @@
 }
 #endif
 
+/*
+ * context_switch - switch to the new MM and the new
+ * thread's register state.
+ */
 static inline task_t * context_switch(task_t *prev, task_t *next)
 {
 	struct mm_struct *mm = next->mm;
@@ -497,6 +536,13 @@
 	return prev;
 }
 
+/*
+ * nr_running, nr_uninterruptible and nr_context_switches:
+ *
+ * externally visible scheduler statistics: current number of runnable
+ * threads, current number of uninterruptible-sleeping threads, total
+ * number of context switches performed since bootup.
+ */
 unsigned long nr_running(void)
 {
 	unsigned long i, sum = 0;
@@ -564,8 +610,10 @@
 #if CONFIG_SMP
 
 /*
- * Lock the busiest runqueue as well, this_rq is locked already.
- * Recalculate nr_running if we have to drop the runqueue lock.
+ * double_lock_balance - lock the busiest runqueue
+ *
+ * this_rq is locked already. Recalculate nr_running if we have to
+ * drop the runqueue lock.
  */
 static inline unsigned int double_lock_balance(runqueue_t *this_rq,
 	runqueue_t *busiest, int this_cpu, int idle, unsigned int nr_running)
@@ -586,6 +634,9 @@
 	return nr_running;
 }
 
+/*
+ * find_busiest_queue - find the busiest runqueue.
+ */
 static inline runqueue_t *find_busiest_queue(runqueue_t *this_rq, int this_cpu, int idle, int *imbalance)
 {
 	int nr_running, load, max_load, i;
@@ -662,7 +713,7 @@
 }
 
 /*
- * Move a task from a remote runqueue to the local runqueue.
+ * pull_task - move a task from a remote runqueue to the local runqueue.
  * Both runqueues must be locked.
  */
 static inline void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p, runqueue_t *this_rq, int this_cpu)
@@ -766,8 +817,8 @@
 }
 
 /*
- * One of the idle_cpu_tick() or the busy_cpu_tick() function will
- * gets called every timer tick, on every CPU. Our balancing action
+ * One of the idle_cpu_tick() and busy_cpu_tick() functions will
+ * get called every timer tick, on every CPU. Our balancing action
  * frequency and balancing agressivity depends on whether the CPU is
  * idle or not.
  *
@@ -852,7 +903,7 @@
 	/*
 	 * The task was running during this tick - update the
 	 * time slice counter and the sleep average. Note: we
-	 * do not update a process's priority until it either
+	 * do not update a thread's priority until it either
 	 * goes to sleep or uses up its timeslice. This makes
 	 * it possible for interactive tasks to use up their
 	 * timeslices at their highest priority levels.
@@ -884,7 +935,7 @@
 void scheduling_functions_start_here(void) { }
 
 /*
- * 'schedule()' is the main scheduler function.
+ * schedule() is the main scheduler function.
  */
 asmlinkage void schedule(void)
 {
@@ -1038,6 +1089,12 @@
 	}
 }
 
+/**
+ * __wake_up - wake up threads blocked on a waitqueue.
+ * @q: the waitqueue
+ * @mode: which threads
+ * @nr_exclusive: how many wake-one or wake-many threads to wake up
+ */
 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
 {
 	unsigned long flags;
@@ -1060,6 +1117,17 @@
 
 #if CONFIG_SMP
 
+/**
+ * __wake_up - sync- wake up threads blocked on a waitqueue.
+ * @q: the waitqueue
+ * @mode: which threads
+ * @nr_exclusive: how many wake-one or wake-many threads to wake up
+ *
+ * The sync wakeup differs that the waker knows that it will schedule
+ * away soon, so while the target thread will be woken up, it will not
+ * be migrated to another CPU - ie. the two threads are 'synchronized'
+ * with each other. This can prevent needless bouncing between CPUs.
+ */
 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
 {
 	unsigned long flags;
@@ -1211,11 +1279,12 @@
 #ifndef __alpha__
 
 /*
- * This has been replaced by sys_setpriority.  Maybe it should be
- * moved into the arch dependent tree for those ports that require
- * it for backward compatibility?
+ * sys_nice - change the priority of the current process.
+ * @increment: priority increment
+ *
+ * sys_setpriority is a more generic, but much slower function that
+ * does similar things.
  */
-
 asmlinkage long sys_nice(int increment)
 {
 	int retval;
@@ -1251,9 +1320,11 @@
 
 #endif
 
-/*
- * This is the priority value as seen by users in /proc
+/**
+ * task_prio - return the priority value of a given task.
+ * @p: the task in question.
  *
+ * This is the priority value as seen by users in /proc.
  * RT tasks are offset by -200. Normal tasks are centered
  * around 0, value goes from -16 to +15.
  */
@@ -1262,21 +1333,36 @@
 	return p->prio - MAX_USER_RT_PRIO;
 }
 
+/**
+ * task_nice - return the nice value of a given task.
+ * @p: the task in question.
+ */
 int task_nice(task_t *p)
 {
 	return TASK_NICE(p);
 }
 
+/**
+ * idle_cpu - is a given cpu idle currently?
+ * @cpu: the processor in question.
+ */
 int idle_cpu(int cpu)
 {
 	return cpu_curr(cpu) == cpu_rq(cpu)->idle;
 }
 
+/**
+ * find_process_by_pid - find a process with a matching PID value.
+ * @pid: the pid in question.
+ */
 static inline task_t *find_process_by_pid(pid_t pid)
 {
 	return pid ? find_task_by_pid(pid) : current;
 }
 
+/*
+ * setscheduler - change the scheduling policy and/or RT priority of a thread.
+ */
 static int setscheduler(pid_t pid, int policy, struct sched_param *param)
 {
 	struct sched_param lp;
@@ -1363,17 +1449,32 @@
 	return retval;
 }
 
+/**
+ * sys_sched_setscheduler - set/change the scheduler policy and RT priority
+ * @pid: the pid in question.
+ * @policy: new policy
+ * @param: structure containing the new RT priority.
+ */
 asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
 				      struct sched_param *param)
 {
 	return setscheduler(pid, policy, param);
 }
 
+/**
+ * sys_sched_setparam - set/change the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the new RT priority.
+ */
 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param *param)
 {
 	return setscheduler(pid, -1, param);
 }
 
+/**
+ * sys_sched_getscheduler - get the policy (scheduling class) of a thread
+ * @pid: the pid in question.
+ */
 asmlinkage long sys_sched_getscheduler(pid_t pid)
 {
 	int retval = -EINVAL;
@@ -1396,6 +1497,11 @@
 	return retval;
 }
 
+/**
+ * sys_sched_getscheduler - get the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the RT priority.
+ */
 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param *param)
 {
 	struct sched_param lp;
@@ -1520,6 +1626,13 @@
 	return real_len;
 }
 
+/**
+ * sys_sched_yield - yield the current processor to other threads.
+ *
+ * this function yields the current CPU by moving the calling thread
+ * to the expired array. If there are no other threads running on this
+ * CPU then this function will return.
+ */
 asmlinkage long sys_sched_yield(void)
 {
 	runqueue_t *rq = this_rq_lock();
@@ -1557,12 +1670,25 @@
 	schedule();
 }
 
+/**
+ * yield - yield the current processor to other threads.
+ *
+ * this is a shortcut for kernel-space yielding - it marks the
+ * thread runnable and calls sys_sched_yield().
+ */
 void yield(void)
 {
 	set_current_state(TASK_RUNNING);
 	sys_sched_yield();
 }
 
+/**
+ * sys_sched_get_priority_max - return maximum RT priority.
+ * @policy: scheduling class.
+ *
+ * this syscall returns the maximum rt_priority that can be used
+ * by a given scheduling class.
+ */
 asmlinkage long sys_sched_get_priority_max(int policy)
 {
 	int ret = -EINVAL;
@@ -1579,6 +1705,13 @@
 	return ret;
 }
 
+/**
+ * sys_sched_get_priority_mix - return minimum RT priority.
+ * @policy: scheduling class.
+ *
+ * this syscall returns the minimum rt_priority that can be used
+ * by a given scheduling class.
+ */
 asmlinkage long sys_sched_get_priority_min(int policy)
 {
 	int ret = -EINVAL;
@@ -1594,6 +1727,14 @@
 	return ret;
 }
 
+/**
+ * sys_sched_rr_get_interval - return the default timeslice of a process.
+ * @pid: pid of the process.
+ * @interval: userspace pointer to the timeslice value.
+ *
+ * this syscall writes the default timeslice value of a given process
+ * into the user-space timespec buffer. A value of '0' means infinity.
+ */
 asmlinkage long sys_sched_rr_get_interval(pid_t pid, struct timespec *interval)
 {
 	int retval = -EINVAL;
@@ -1769,7 +1910,7 @@
 } migration_req_t;
 
 /*
- * Change a given task's CPU affinity. Migrate the process to a
+ * Change a given task's CPU affinity. Migrate the thread to a
  * proper CPU and schedule it away if the CPU it's executing on
  * is removed from the allowed bitmask.
  *
@@ -1794,7 +1935,7 @@
 	p->cpus_allowed = new_mask;
 	/*
 	 * Can the task run on the task's current CPU? If not then
-	 * migrate the process off to a proper CPU.
+	 * migrate the thread off to a proper CPU.
 	 */
 	if (new_mask & (1UL << task_cpu(p))) {
 		task_rq_unlock(rq, &flags);
@@ -1843,11 +1984,15 @@
 	return 0;
 }
 
-static int migration_thread(void * bind_cpu)
+/*
+ * migration_thread - this is a highprio system thread that performs
+ * thread migration by 'pulling' threads into the target runqueue.
+ */
+static int migration_thread(void * data)
 {
-	int cpu = (int) (long) bind_cpu;
 	struct sched_param param = { sched_priority: MAX_RT_PRIO-1 };
 	migration_startup_t startup;
+	int cpu = (long) data;
 	runqueue_t *rq;
 	int ret, pid;
 
@@ -1859,6 +2004,13 @@
 	startup.thread = current;
 	pid = kernel_thread(migration_startup_thread, &startup,
 		CLONE_FS | CLONE_FILES | CLONE_SIGNAL);
+
+	/*
+	 * Migration can happen without a migration thread on the
+	 * target CPU because here we remove the thread from the
+	 * runqueue and the helper thread then moves this thread
+	 * to the target CPU - we'll wake up there.
+	 */
 	down(&migration_startup);
 
 	/* we need to waitpid() to release the helper thread */
@@ -1868,7 +2020,7 @@
 	 * At this point the startup helper thread must have
 	 * migrated us to the proper CPU already:
 	 */
-	if (smp_processor_id() != (int)bind_cpu)
+	if (smp_processor_id() != cpu)
 		BUG();
 
 	printk("migration_task %d on cpu=%d\n", cpu, smp_processor_id());
@@ -1927,6 +2079,10 @@
 	}
 }
 
+/*
+ * migration_call - callback that gets triggered when a CPU is added.
+ * Here we can start up the necessary migration thread for the new CPU.
+ */
 static int migration_call(struct notifier_block *nfb,
 			  unsigned long action,
 			  void *hcpu)
@@ -1989,7 +2145,7 @@
 	}
 	/*
 	 * We have to do a little magic to get the first
-	 * process right in SMP mode.
+	 * thread right in SMP mode.
 	 */
 	rq = this_rq();
 	rq->curr = current;

[patch] APM fixes, 2.5.29

[Ingo Molnar]

the attached patch fixes two things:

 - a TLS related bug noticed by Arjan van de Ven: apm_init() should set up 
   all CPU's gdt entries - just in case some code happens to call in the
   APM BIOS on the wrong CPU. This should also handle the case when some 
   APM code gets triggered (by suspend or power button or something).

 - compilation problem

	Ingo

--- linux/arch/i386/kernel/apm.c.orig	Sun Jul 28 11:58:55 2002
+++ linux/arch/i386/kernel/apm.c	Sun Jul 28 13:27:54 2002
@@ -1589,7 +1589,7 @@
 
 	p = buf;
 
-	if ((num_possible_cpus() == 1) &&
+	if ((num_online_cpus() == 1) &&
 	    !(error = apm_get_power_status(&bx, &cx, &dx))) {
 		ac_line_status = (bx >> 8) & 0xff;
 		battery_status = bx & 0xff;
@@ -1720,7 +1720,7 @@
 		}
 	}
 
-	if (debug && (num_possible_cpus() == 1)) {
+	if (debug && (num_online_cpus() == 1)) {
 		error = apm_get_power_status(&bx, &cx, &dx);
 		if (error)
 			printk(KERN_INFO "apm: power status not available\n");
@@ -1764,7 +1764,7 @@
 		pm_power_off = apm_power_off;
 	register_sysrq_key('o', &sysrq_poweroff_op);
 
-	if (num_possible_cpus() == 1) {
+	if (num_online_cpus() == 1) {
 #if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)
 		console_blank_hook = apm_console_blank;
 #endif
@@ -1853,6 +1853,7 @@
 static int __init apm_init(void)
 {
 	struct proc_dir_entry *apm_proc;
+	int i;
 
 	if (apm_info.bios.version == 0) {
 		printk(KERN_INFO "apm: BIOS not found.\n");
@@ -1907,7 +1908,7 @@
 		printk(KERN_NOTICE "apm: disabled on user request.\n");
 		return -ENODEV;
 	}
-	if ((num_possible_cpus() > 1) && !power_off) {
+	if ((num_online_cpus() > 1) && !power_off) {
 		printk(KERN_NOTICE "apm: disabled - APM is not SMP safe.\n");
 		return -ENODEV;
 	}
@@ -1926,37 +1927,39 @@
 	 * NOTE: on SMP we call into the APM BIOS only on CPU#0, so it's
 	 * enough to modify CPU#0's GDT.
 	 */
-	set_base(cpu_gdt_table[0][APM_40 >> 3],
-		 __va((unsigned long)0x40 << 4));
-	_set_limit((char *)&cpu_gdt_table[0][APM_40 >> 3], 4095 - (0x40 << 4));
-
-	apm_bios_entry.offset = apm_info.bios.offset;
-	apm_bios_entry.segment = APM_CS;
-	set_base(cpu_gdt_table[0][APM_CS >> 3],
-		 __va((unsigned long)apm_info.bios.cseg << 4));
-	set_base(cpu_gdt_table[0][APM_CS_16 >> 3],
-		 __va((unsigned long)apm_info.bios.cseg_16 << 4));
-	set_base(cpu_gdt_table[0][APM_DS >> 3],
-		 __va((unsigned long)apm_info.bios.dseg << 4));
+	for (i = 0; i < NR_CPUS; i++) {
+		set_base(cpu_gdt_table[i][APM_40 >> 3],
+			 __va((unsigned long)0x40 << 4));
+		_set_limit((char *)&cpu_gdt_table[i][APM_40 >> 3], 4095 - (0x40 << 4));
+
+		apm_bios_entry.offset = apm_info.bios.offset;
+		apm_bios_entry.segment = APM_CS;
+		set_base(cpu_gdt_table[i][APM_CS >> 3],
+			 __va((unsigned long)apm_info.bios.cseg << 4));
+		set_base(cpu_gdt_table[i][APM_CS_16 >> 3],
+			 __va((unsigned long)apm_info.bios.cseg_16 << 4));
+		set_base(cpu_gdt_table[i][APM_DS >> 3],
+			 __va((unsigned long)apm_info.bios.dseg << 4));
 #ifndef APM_RELAX_SEGMENTS
-	if (apm_info.bios.version == 0x100) {
+		if (apm_info.bios.version == 0x100) {
 #endif
-		/* For ASUS motherboard, Award BIOS rev 110 (and others?) */
-		_set_limit((char *)&cpu_gdt_table[0][APM_CS >> 3], 64 * 1024 - 1);
-		/* For some unknown machine. */
-		_set_limit((char *)&cpu_gdt_table[0][APM_CS_16 >> 3], 64 * 1024 - 1);
-		/* For the DEC Hinote Ultra CT475 (and others?) */
-		_set_limit((char *)&cpu_gdt_table[0][APM_DS >> 3], 64 * 1024 - 1);
+			/* For ASUS motherboard, Award BIOS rev 110 (and others?) */
+			_set_limit((char *)&cpu_gdt_table[i][APM_CS >> 3], 64 * 1024 - 1);
+			/* For some unknown machine. */
+			_set_limit((char *)&cpu_gdt_table[i][APM_CS_16 >> 3], 64 * 1024 - 1);
+			/* For the DEC Hinote Ultra CT475 (and others?) */
+			_set_limit((char *)&cpu_gdt_table[i][APM_DS >> 3], 64 * 1024 - 1);
 #ifndef APM_RELAX_SEGMENTS
-	} else {
-		_set_limit((char *)&cpu_gdt_table[0][APM_CS >> 3],
-			(apm_info.bios.cseg_len - 1) & 0xffff);
-		_set_limit((char *)&cpu_gdt_table[0][APM_CS_16 >> 3],
-			(apm_info.bios.cseg_16_len - 1) & 0xffff);
-		_set_limit((char *)&cpu_gdt_table[0][APM_DS >> 3],
-			(apm_info.bios.dseg_len - 1) & 0xffff);
-	}
+		} else {
+			_set_limit((char *)&cpu_gdt_table[i][APM_CS >> 3],
+				(apm_info.bios.cseg_len - 1) & 0xffff);
+			_set_limit((char *)&cpu_gdt_table[i][APM_CS_16 >> 3],
+				(apm_info.bios.cseg_16_len - 1) & 0xffff);
+			_set_limit((char *)&cpu_gdt_table[i][APM_DS >> 3],
+				(apm_info.bios.dseg_len - 1) & 0xffff);
+		}
 #endif
+	}
 
 	apm_proc = create_proc_info_entry("apm", 0, NULL, apm_get_info);
 	if (apm_proc)
@@ -1964,7 +1967,7 @@
 
 	kernel_thread(apm, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND | SIGCHLD);
 
-	if (num_possible_cpus() > 1) {
+	if (num_online_cpus() > 1) {
 		printk(KERN_NOTICE
 		   "apm: disabled - APM is not SMP safe (power off active).\n");
 		return 0;

Re: [patch] APM fixes, 2.5.29

[Stephen Rothwell]

Hi Ingo,

On Sun, 28 Jul 2002 13:28:34 +0200 (CEST) Ingo Molnar <mingo@elte.hu> wrote:
>
> 
> the attached patch fixes two things:
> 
>  - a TLS related bug noticed by Arjan van de Ven: apm_init() should set up 
>    all CPU's gdt entries - just in case some code happens to call in the
>    APM BIOS on the wrong CPU. This should also handle the case when some 
>    APM code gets triggered (by suspend or power button or something).

Except, if you read the comment, we never do APM BIOS calls on anything
but CPU 0.  On SMP the only APM BIOS operation we allow is power off
and we have code to ensure we are on CPU 0 before we do that ...

>  - compilation problem

I would prefer a patch (see the post by Muli Ben-Yehuda
<mulix@actcom.co.il>) that defines num_possible_cpus() or equivalent, the
current code (using num_online_cpus()) is broken in places.

I need to revisit all this code in light of CPU hotplug ...
-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

Re: [patch] APM fixes, 2.5.29

[Alan Cox]

On Mon, 2002-07-29 at 04:05, Stephen Rothwell wrote:
> Except, if you read the comment, we never do APM BIOS calls on anything
> but CPU 0.  On SMP the only APM BIOS operation we allow is power off
> and we have code to ensure we are on CPU 0 before we do that .


Until I merge the -ac patch that allows you to force APM on SMP boxes
for the few cases it works right.