1 /* 2 * Virtual cpu timer based timer functions. 3 * 4 * Copyright IBM Corp. 2004, 2012 5 * Author(s): Jan Glauber <jan.glauber@de.ibm.com> 6 */ 7 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> 14 15 #include <asm/cputime.h> 16 #include <asm/vtimer.h> 17 #include <asm/vtime.h> 18 #include <asm/cpu_mf.h> 19 #include <asm/smp.h> 20 21 #include "entry.h" 22 23 static void virt_timer_expire(void); 24 25 static LIST_HEAD(virt_timer_list); 26 static DEFINE_SPINLOCK(virt_timer_lock); 27 static atomic64_t virt_timer_current; 28 static atomic64_t virt_timer_elapsed; 29 30 DEFINE_PER_CPU(u64, mt_cycles[8]); 31 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 }; 32 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 }; 33 static DEFINE_PER_CPU(u64, mt_scaling_jiffies); 34 35 static inline u64 get_vtimer(void) 36 { 37 u64 timer; 38 39 asm volatile("stpt %0" : "=m" (timer)); 40 return timer; 41 } 42 43 static inline void set_vtimer(u64 expires) 44 { 45 u64 timer; 46 47 asm volatile( 48 " stpt %0\n" /* Store current cpu timer value */ 49 " spt %1" /* Set new value imm. afterwards */ 50 : "=m" (timer) : "m" (expires)); 51 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer; 52 S390_lowcore.last_update_timer = expires; 53 } 54 55 static inline int virt_timer_forward(u64 elapsed) 56 { 57 BUG_ON(!irqs_disabled()); 58 59 if (list_empty(&virt_timer_list)) 60 return 0; 61 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed); 62 return elapsed >= atomic64_read(&virt_timer_current); 63 } 64 65 static void update_mt_scaling(void) 66 { 67 u64 cycles_new[8], *cycles_old; 68 u64 delta, fac, mult, div; 69 int i; 70 71 stcctm5(smp_cpu_mtid + 1, cycles_new); 72 cycles_old = this_cpu_ptr(mt_cycles); 73 fac = 1; 74 mult = div = 0; 75 for (i = 0; i <= smp_cpu_mtid; i++) { 76 delta = cycles_new[i] - cycles_old[i]; 77 div += delta; 78 mult *= i + 1; 79 mult += delta * fac; 80 fac *= i + 1; 81 } 82 div *= fac; 83 if (div > 0) { 84 /* Update scaling factor */ 85 __this_cpu_write(mt_scaling_mult, mult); 86 __this_cpu_write(mt_scaling_div, div); 87 memcpy(cycles_old, cycles_new, 88 sizeof(u64) * (smp_cpu_mtid + 1)); 89 } 90 __this_cpu_write(mt_scaling_jiffies, jiffies_64); 91 } 92 93 /* 94 * Update process times based on virtual cpu times stored by entry.S 95 * to the lowcore fields user_timer, system_timer & steal_clock. 96 */ 97 static int do_account_vtime(struct task_struct *tsk) 98 { 99 u64 timer, clock, user, system, steal; 100 u64 user_scaled, system_scaled; 101 102 timer = S390_lowcore.last_update_timer; 103 clock = S390_lowcore.last_update_clock; 104 asm volatile( 105 " stpt %0\n" /* Store current cpu timer value */ 106 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES 107 " stckf %1" /* Store current tod clock value */ 108 #else 109 " stck %1" /* Store current tod clock value */ 110 #endif 111 : "=m" (S390_lowcore.last_update_timer), 112 "=m" (S390_lowcore.last_update_clock)); 113 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer; 114 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock; 115 116 /* Update MT utilization calculation */ 117 if (smp_cpu_mtid && 118 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 119 update_mt_scaling(); 120 121 user = S390_lowcore.user_timer - tsk->thread.user_timer; 122 S390_lowcore.steal_timer -= user; 123 tsk->thread.user_timer = S390_lowcore.user_timer; 124 125 system = S390_lowcore.system_timer - tsk->thread.system_timer; 126 S390_lowcore.steal_timer -= system; 127 tsk->thread.system_timer = S390_lowcore.system_timer; 128 129 user_scaled = user; 130 system_scaled = system; 131 /* Do MT utilization scaling */ 132 if (smp_cpu_mtid) { 133 u64 mult = __this_cpu_read(mt_scaling_mult); 134 u64 div = __this_cpu_read(mt_scaling_div); 135 136 user_scaled = (user_scaled * mult) / div; 137 system_scaled = (system_scaled * mult) / div; 138 } 139 account_user_time(tsk, user); 140 tsk->utimescaled += user_scaled; 141 account_system_time(tsk, 0, system); 142 tsk->stimescaled += system_scaled; 143 144 steal = S390_lowcore.steal_timer; 145 if ((s64) steal > 0) { 146 S390_lowcore.steal_timer = 0; 147 account_steal_time(steal); 148 } 149 150 return virt_timer_forward(user + system); 151 } 152 153 void vtime_task_switch(struct task_struct *prev) 154 { 155 do_account_vtime(prev); 156 prev->thread.user_timer = S390_lowcore.user_timer; 157 prev->thread.system_timer = S390_lowcore.system_timer; 158 S390_lowcore.user_timer = current->thread.user_timer; 159 S390_lowcore.system_timer = current->thread.system_timer; 160 } 161 162 /* 163 * In s390, accounting pending user time also implies 164 * accounting system time in order to correctly compute 165 * the stolen time accounting. 166 */ 167 void vtime_account_user(struct task_struct *tsk) 168 { 169 if (do_account_vtime(tsk)) 170 virt_timer_expire(); 171 } 172 173 /* 174 * Update process times based on virtual cpu times stored by entry.S 175 * to the lowcore fields user_timer, system_timer & steal_clock. 176 */ 177 void vtime_account_irq_enter(struct task_struct *tsk) 178 { 179 u64 timer, system, system_scaled; 180 181 timer = S390_lowcore.last_update_timer; 182 S390_lowcore.last_update_timer = get_vtimer(); 183 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer; 184 185 /* Update MT utilization calculation */ 186 if (smp_cpu_mtid && 187 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 188 update_mt_scaling(); 189 190 system = S390_lowcore.system_timer - tsk->thread.system_timer; 191 S390_lowcore.steal_timer -= system; 192 tsk->thread.system_timer = S390_lowcore.system_timer; 193 system_scaled = system; 194 /* Do MT utilization scaling */ 195 if (smp_cpu_mtid) { 196 u64 mult = __this_cpu_read(mt_scaling_mult); 197 u64 div = __this_cpu_read(mt_scaling_div); 198 199 system_scaled = (system_scaled * mult) / div; 200 } 201 account_system_time(tsk, 0, system); 202 tsk->stimescaled += system_scaled; 203 204 virt_timer_forward(system); 205 } 206 EXPORT_SYMBOL_GPL(vtime_account_irq_enter); 207 208 void vtime_account_system(struct task_struct *tsk) 209 __attribute__((alias("vtime_account_irq_enter"))); 210 EXPORT_SYMBOL_GPL(vtime_account_system); 211 212 /* 213 * Sorted add to a list. List is linear searched until first bigger 214 * element is found. 215 */ 216 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 217 { 218 struct vtimer_list *tmp; 219 220 list_for_each_entry(tmp, head, entry) { 221 if (tmp->expires > timer->expires) { 222 list_add_tail(&timer->entry, &tmp->entry); 223 return; 224 } 225 } 226 list_add_tail(&timer->entry, head); 227 } 228 229 /* 230 * Handler for expired virtual CPU timer. 231 */ 232 static void virt_timer_expire(void) 233 { 234 struct vtimer_list *timer, *tmp; 235 unsigned long elapsed; 236 LIST_HEAD(cb_list); 237 238 /* walk timer list, fire all expired timers */ 239 spin_lock(&virt_timer_lock); 240 elapsed = atomic64_read(&virt_timer_elapsed); 241 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 242 if (timer->expires < elapsed) 243 /* move expired timer to the callback queue */ 244 list_move_tail(&timer->entry, &cb_list); 245 else 246 timer->expires -= elapsed; 247 } 248 if (!list_empty(&virt_timer_list)) { 249 timer = list_first_entry(&virt_timer_list, 250 struct vtimer_list, entry); 251 atomic64_set(&virt_timer_current, timer->expires); 252 } 253 atomic64_sub(elapsed, &virt_timer_elapsed); 254 spin_unlock(&virt_timer_lock); 255 256 /* Do callbacks and recharge periodic timers */ 257 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 258 list_del_init(&timer->entry); 259 timer->function(timer->data); 260 if (timer->interval) { 261 /* Recharge interval timer */ 262 timer->expires = timer->interval + 263 atomic64_read(&virt_timer_elapsed); 264 spin_lock(&virt_timer_lock); 265 list_add_sorted(timer, &virt_timer_list); 266 spin_unlock(&virt_timer_lock); 267 } 268 } 269 } 270 271 void init_virt_timer(struct vtimer_list *timer) 272 { 273 timer->function = NULL; 274 INIT_LIST_HEAD(&timer->entry); 275 } 276 EXPORT_SYMBOL(init_virt_timer); 277 278 static inline int vtimer_pending(struct vtimer_list *timer) 279 { 280 return !list_empty(&timer->entry); 281 } 282 283 static void internal_add_vtimer(struct vtimer_list *timer) 284 { 285 if (list_empty(&virt_timer_list)) { 286 /* First timer, just program it. */ 287 atomic64_set(&virt_timer_current, timer->expires); 288 atomic64_set(&virt_timer_elapsed, 0); 289 list_add(&timer->entry, &virt_timer_list); 290 } else { 291 /* Update timer against current base. */ 292 timer->expires += atomic64_read(&virt_timer_elapsed); 293 if (likely((s64) timer->expires < 294 (s64) atomic64_read(&virt_timer_current))) 295 /* The new timer expires before the current timer. */ 296 atomic64_set(&virt_timer_current, timer->expires); 297 /* Insert new timer into the list. */ 298 list_add_sorted(timer, &virt_timer_list); 299 } 300 } 301 302 static void __add_vtimer(struct vtimer_list *timer, int periodic) 303 { 304 unsigned long flags; 305 306 timer->interval = periodic ? timer->expires : 0; 307 spin_lock_irqsave(&virt_timer_lock, flags); 308 internal_add_vtimer(timer); 309 spin_unlock_irqrestore(&virt_timer_lock, flags); 310 } 311 312 /* 313 * add_virt_timer - add an oneshot virtual CPU timer 314 */ 315 void add_virt_timer(struct vtimer_list *timer) 316 { 317 __add_vtimer(timer, 0); 318 } 319 EXPORT_SYMBOL(add_virt_timer); 320 321 /* 322 * add_virt_timer_int - add an interval virtual CPU timer 323 */ 324 void add_virt_timer_periodic(struct vtimer_list *timer) 325 { 326 __add_vtimer(timer, 1); 327 } 328 EXPORT_SYMBOL(add_virt_timer_periodic); 329 330 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 331 { 332 unsigned long flags; 333 int rc; 334 335 BUG_ON(!timer->function); 336 337 if (timer->expires == expires && vtimer_pending(timer)) 338 return 1; 339 spin_lock_irqsave(&virt_timer_lock, flags); 340 rc = vtimer_pending(timer); 341 if (rc) 342 list_del_init(&timer->entry); 343 timer->interval = periodic ? expires : 0; 344 timer->expires = expires; 345 internal_add_vtimer(timer); 346 spin_unlock_irqrestore(&virt_timer_lock, flags); 347 return rc; 348 } 349 350 /* 351 * returns whether it has modified a pending timer (1) or not (0) 352 */ 353 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 354 { 355 return __mod_vtimer(timer, expires, 0); 356 } 357 EXPORT_SYMBOL(mod_virt_timer); 358 359 /* 360 * returns whether it has modified a pending timer (1) or not (0) 361 */ 362 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 363 { 364 return __mod_vtimer(timer, expires, 1); 365 } 366 EXPORT_SYMBOL(mod_virt_timer_periodic); 367 368 /* 369 * Delete a virtual timer. 370 * 371 * returns whether the deleted timer was pending (1) or not (0) 372 */ 373 int del_virt_timer(struct vtimer_list *timer) 374 { 375 unsigned long flags; 376 377 if (!vtimer_pending(timer)) 378 return 0; 379 spin_lock_irqsave(&virt_timer_lock, flags); 380 list_del_init(&timer->entry); 381 spin_unlock_irqrestore(&virt_timer_lock, flags); 382 return 1; 383 } 384 EXPORT_SYMBOL(del_virt_timer); 385 386 /* 387 * Start the virtual CPU timer on the current CPU. 388 */ 389 void vtime_init(void) 390 { 391 /* set initial cpu timer */ 392 set_vtimer(VTIMER_MAX_SLICE); 393 /* Setup initial MT scaling values */ 394 if (smp_cpu_mtid) { 395 __this_cpu_write(mt_scaling_jiffies, jiffies); 396 __this_cpu_write(mt_scaling_mult, 1); 397 __this_cpu_write(mt_scaling_div, 1); 398 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 399 } 400 } 401