2 * Virtual cpu timer based timer functions.
4 * Copyright IBM Corp. 2004, 2012
5 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
8 #include <linux/kernel_stat.h>
9 #include <linux/export.h>
10 #include <linux/kernel.h>
11 #include <linux/timex.h>
12 #include <linux/types.h>
13 #include <linux/time.h>
15 #include <asm/cputime.h>
16 #include <asm/vtimer.h>
17 #include <asm/vtime.h>
18 #include <asm/cpu_mf.h>
21 static void virt_timer_expire(void);
23 static LIST_HEAD(virt_timer_list);
24 static DEFINE_SPINLOCK(virt_timer_lock);
25 static atomic64_t virt_timer_current;
26 static atomic64_t virt_timer_elapsed;
28 static DEFINE_PER_CPU(u64, mt_cycles[32]);
29 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
30 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
31 static DEFINE_PER_CPU(u64, mt_scaling_jiffies);
33 static inline u64 get_vtimer(void)
37 asm volatile("stpt %0" : "=m" (timer));
41 static inline void set_vtimer(u64 expires)
46 " stpt %0\n" /* Store current cpu timer value */
47 " spt %1" /* Set new value imm. afterwards */
48 : "=m" (timer) : "m" (expires));
49 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
50 S390_lowcore.last_update_timer = expires;
53 static inline int virt_timer_forward(u64 elapsed)
55 BUG_ON(!irqs_disabled());
57 if (list_empty(&virt_timer_list))
59 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
60 return elapsed >= atomic64_read(&virt_timer_current);
64 * Update process times based on virtual cpu times stored by entry.S
65 * to the lowcore fields user_timer, system_timer & steal_clock.
67 static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
69 struct thread_info *ti = task_thread_info(tsk);
70 u64 timer, clock, user, system, steal;
71 u64 user_scaled, system_scaled;
74 timer = S390_lowcore.last_update_timer;
75 clock = S390_lowcore.last_update_clock;
77 " stpt %0\n" /* Store current cpu timer value */
78 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
79 " stckf %1" /* Store current tod clock value */
81 " stck %1" /* Store current tod clock value */
83 : "=m" (S390_lowcore.last_update_timer),
84 "=m" (S390_lowcore.last_update_clock));
85 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
86 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
88 /* Do MT utilization calculation */
90 time_after64(jiffies_64, __this_cpu_read(mt_scaling_jiffies))) {
91 u64 cycles_new[32], *cycles_old;
92 u64 delta, fac, mult, div;
94 cycles_old = this_cpu_ptr(mt_cycles);
95 if (stcctm5(smp_cpu_mtid + 1, cycles_new) < 2) {
98 for (i = 0; i <= smp_cpu_mtid; i++) {
99 delta = cycles_new[i] - cycles_old[i];
107 /* Update scaling factor */
108 __this_cpu_write(mt_scaling_mult, mult);
109 __this_cpu_write(mt_scaling_div, div);
110 memcpy(cycles_old, cycles_new,
111 sizeof(u64) * (smp_cpu_mtid + 1));
114 __this_cpu_write(mt_scaling_jiffies, jiffies_64);
117 user = S390_lowcore.user_timer - ti->user_timer;
118 S390_lowcore.steal_timer -= user;
119 ti->user_timer = S390_lowcore.user_timer;
121 system = S390_lowcore.system_timer - ti->system_timer;
122 S390_lowcore.steal_timer -= system;
123 ti->system_timer = S390_lowcore.system_timer;
126 system_scaled = system;
127 /* Do MT utilization scaling */
129 u64 mult = __this_cpu_read(mt_scaling_mult);
130 u64 div = __this_cpu_read(mt_scaling_div);
132 user_scaled = (user_scaled * mult) / div;
133 system_scaled = (system_scaled * mult) / div;
135 account_user_time(tsk, user, user_scaled);
136 account_system_time(tsk, hardirq_offset, system, system_scaled);
138 steal = S390_lowcore.steal_timer;
139 if ((s64) steal > 0) {
140 S390_lowcore.steal_timer = 0;
141 account_steal_time(steal);
144 return virt_timer_forward(user + system);
147 void vtime_task_switch(struct task_struct *prev)
149 struct thread_info *ti;
151 do_account_vtime(prev, 0);
152 ti = task_thread_info(prev);
153 ti->user_timer = S390_lowcore.user_timer;
154 ti->system_timer = S390_lowcore.system_timer;
155 ti = task_thread_info(current);
156 S390_lowcore.user_timer = ti->user_timer;
157 S390_lowcore.system_timer = ti->system_timer;
161 * In s390, accounting pending user time also implies
162 * accounting system time in order to correctly compute
163 * the stolen time accounting.
165 void vtime_account_user(struct task_struct *tsk)
167 if (do_account_vtime(tsk, HARDIRQ_OFFSET))
172 * Update process times based on virtual cpu times stored by entry.S
173 * to the lowcore fields user_timer, system_timer & steal_clock.
175 void vtime_account_irq_enter(struct task_struct *tsk)
177 struct thread_info *ti = task_thread_info(tsk);
178 u64 timer, system, system_scaled;
180 timer = S390_lowcore.last_update_timer;
181 S390_lowcore.last_update_timer = get_vtimer();
182 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
184 system = S390_lowcore.system_timer - ti->system_timer;
185 S390_lowcore.steal_timer -= system;
186 ti->system_timer = S390_lowcore.system_timer;
187 system_scaled = system;
188 /* Do MT utilization scaling */
190 u64 mult = __this_cpu_read(mt_scaling_mult);
191 u64 div = __this_cpu_read(mt_scaling_div);
193 system_scaled = (system_scaled * mult) / div;
195 account_system_time(tsk, 0, system, system_scaled);
197 virt_timer_forward(system);
199 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
201 void vtime_account_system(struct task_struct *tsk)
202 __attribute__((alias("vtime_account_irq_enter")));
203 EXPORT_SYMBOL_GPL(vtime_account_system);
206 * Sorted add to a list. List is linear searched until first bigger
209 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
211 struct vtimer_list *tmp;
213 list_for_each_entry(tmp, head, entry) {
214 if (tmp->expires > timer->expires) {
215 list_add_tail(&timer->entry, &tmp->entry);
219 list_add_tail(&timer->entry, head);
223 * Handler for expired virtual CPU timer.
225 static void virt_timer_expire(void)
227 struct vtimer_list *timer, *tmp;
228 unsigned long elapsed;
231 /* walk timer list, fire all expired timers */
232 spin_lock(&virt_timer_lock);
233 elapsed = atomic64_read(&virt_timer_elapsed);
234 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
235 if (timer->expires < elapsed)
236 /* move expired timer to the callback queue */
237 list_move_tail(&timer->entry, &cb_list);
239 timer->expires -= elapsed;
241 if (!list_empty(&virt_timer_list)) {
242 timer = list_first_entry(&virt_timer_list,
243 struct vtimer_list, entry);
244 atomic64_set(&virt_timer_current, timer->expires);
246 atomic64_sub(elapsed, &virt_timer_elapsed);
247 spin_unlock(&virt_timer_lock);
249 /* Do callbacks and recharge periodic timers */
250 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
251 list_del_init(&timer->entry);
252 timer->function(timer->data);
253 if (timer->interval) {
254 /* Recharge interval timer */
255 timer->expires = timer->interval +
256 atomic64_read(&virt_timer_elapsed);
257 spin_lock(&virt_timer_lock);
258 list_add_sorted(timer, &virt_timer_list);
259 spin_unlock(&virt_timer_lock);
264 void init_virt_timer(struct vtimer_list *timer)
266 timer->function = NULL;
267 INIT_LIST_HEAD(&timer->entry);
269 EXPORT_SYMBOL(init_virt_timer);
271 static inline int vtimer_pending(struct vtimer_list *timer)
273 return !list_empty(&timer->entry);
276 static void internal_add_vtimer(struct vtimer_list *timer)
278 if (list_empty(&virt_timer_list)) {
279 /* First timer, just program it. */
280 atomic64_set(&virt_timer_current, timer->expires);
281 atomic64_set(&virt_timer_elapsed, 0);
282 list_add(&timer->entry, &virt_timer_list);
284 /* Update timer against current base. */
285 timer->expires += atomic64_read(&virt_timer_elapsed);
286 if (likely((s64) timer->expires <
287 (s64) atomic64_read(&virt_timer_current)))
288 /* The new timer expires before the current timer. */
289 atomic64_set(&virt_timer_current, timer->expires);
290 /* Insert new timer into the list. */
291 list_add_sorted(timer, &virt_timer_list);
295 static void __add_vtimer(struct vtimer_list *timer, int periodic)
299 timer->interval = periodic ? timer->expires : 0;
300 spin_lock_irqsave(&virt_timer_lock, flags);
301 internal_add_vtimer(timer);
302 spin_unlock_irqrestore(&virt_timer_lock, flags);
306 * add_virt_timer - add an oneshot virtual CPU timer
308 void add_virt_timer(struct vtimer_list *timer)
310 __add_vtimer(timer, 0);
312 EXPORT_SYMBOL(add_virt_timer);
315 * add_virt_timer_int - add an interval virtual CPU timer
317 void add_virt_timer_periodic(struct vtimer_list *timer)
319 __add_vtimer(timer, 1);
321 EXPORT_SYMBOL(add_virt_timer_periodic);
323 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
328 BUG_ON(!timer->function);
330 if (timer->expires == expires && vtimer_pending(timer))
332 spin_lock_irqsave(&virt_timer_lock, flags);
333 rc = vtimer_pending(timer);
335 list_del_init(&timer->entry);
336 timer->interval = periodic ? expires : 0;
337 timer->expires = expires;
338 internal_add_vtimer(timer);
339 spin_unlock_irqrestore(&virt_timer_lock, flags);
344 * returns whether it has modified a pending timer (1) or not (0)
346 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
348 return __mod_vtimer(timer, expires, 0);
350 EXPORT_SYMBOL(mod_virt_timer);
353 * returns whether it has modified a pending timer (1) or not (0)
355 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
357 return __mod_vtimer(timer, expires, 1);
359 EXPORT_SYMBOL(mod_virt_timer_periodic);
362 * Delete a virtual timer.
364 * returns whether the deleted timer was pending (1) or not (0)
366 int del_virt_timer(struct vtimer_list *timer)
370 if (!vtimer_pending(timer))
372 spin_lock_irqsave(&virt_timer_lock, flags);
373 list_del_init(&timer->entry);
374 spin_unlock_irqrestore(&virt_timer_lock, flags);
377 EXPORT_SYMBOL(del_virt_timer);
380 * Start the virtual CPU timer on the current CPU.
382 void vtime_init(void)
384 /* set initial cpu timer */
385 set_vtimer(VTIMER_MAX_SLICE);
386 /* Setup initial MT scaling values */
388 __this_cpu_write(mt_scaling_jiffies, jiffies);
389 __this_cpu_write(mt_scaling_mult, 1);
390 __this_cpu_write(mt_scaling_div, 1);
391 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));