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, int hardirq_offset) 98 { 99 struct thread_info *ti = task_thread_info(tsk); 100 u64 timer, clock, user, system, steal; 101 u64 user_scaled, system_scaled; 102 103 timer = S390_lowcore.last_update_timer; 104 clock = S390_lowcore.last_update_clock; 105 asm volatile( 106 " stpt %0\n" /* Store current cpu timer value */ 107 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES 108 " stckf %1" /* Store current tod clock value */ 109 #else 110 " stck %1" /* Store current tod clock value */ 111 #endif 112 : "=m" (S390_lowcore.last_update_timer), 113 "=m" (S390_lowcore.last_update_clock)); 114 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer; 115 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock; 116 117 /* Update MT utilization calculation */ 118 if (smp_cpu_mtid && 119 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 120 update_mt_scaling(); 121 122 user = S390_lowcore.user_timer - ti->user_timer; 123 S390_lowcore.steal_timer -= user; 124 ti->user_timer = S390_lowcore.user_timer; 125 126 system = S390_lowcore.system_timer - ti->system_timer; 127 S390_lowcore.steal_timer -= system; 128 ti->system_timer = S390_lowcore.system_timer; 129 130 user_scaled = user; 131 system_scaled = system; 132 /* Do MT utilization scaling */ 133 if (smp_cpu_mtid) { 134 u64 mult = __this_cpu_read(mt_scaling_mult); 135 u64 div = __this_cpu_read(mt_scaling_div); 136 137 user_scaled = (user_scaled * mult) / div; 138 system_scaled = (system_scaled * mult) / div; 139 } 140 account_user_time(tsk, user, user_scaled); 141 account_system_time(tsk, hardirq_offset, system, system_scaled); 142 143 steal = S390_lowcore.steal_timer; 144 if ((s64) steal > 0) { 145 S390_lowcore.steal_timer = 0; 146 account_steal_time(steal); 147 } 148 149 return virt_timer_forward(user + system); 150 } 151 152 void vtime_task_switch(struct task_struct *prev) 153 { 154 struct thread_info *ti; 155 156 do_account_vtime(prev, 0); 157 ti = task_thread_info(prev); 158 ti->user_timer = S390_lowcore.user_timer; 159 ti->system_timer = S390_lowcore.system_timer; 160 ti = task_thread_info(current); 161 S390_lowcore.user_timer = ti->user_timer; 162 S390_lowcore.system_timer = ti->system_timer; 163 } 164 165 /* 166 * In s390, accounting pending user time also implies 167 * accounting system time in order to correctly compute 168 * the stolen time accounting. 169 */ 170 void vtime_account_user(struct task_struct *tsk) 171 { 172 if (do_account_vtime(tsk, HARDIRQ_OFFSET)) 173 virt_timer_expire(); 174 } 175 176 /* 177 * Update process times based on virtual cpu times stored by entry.S 178 * to the lowcore fields user_timer, system_timer & steal_clock. 179 */ 180 void vtime_account_irq_enter(struct task_struct *tsk) 181 { 182 struct thread_info *ti = task_thread_info(tsk); 183 u64 timer, system, system_scaled; 184 185 timer = S390_lowcore.last_update_timer; 186 S390_lowcore.last_update_timer = get_vtimer(); 187 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer; 188 189 /* Update MT utilization calculation */ 190 if (smp_cpu_mtid && 191 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies))) 192 update_mt_scaling(); 193 194 system = S390_lowcore.system_timer - ti->system_timer; 195 S390_lowcore.steal_timer -= system; 196 ti->system_timer = S390_lowcore.system_timer; 197 system_scaled = system; 198 /* Do MT utilization scaling */ 199 if (smp_cpu_mtid) { 200 u64 mult = __this_cpu_read(mt_scaling_mult); 201 u64 div = __this_cpu_read(mt_scaling_div); 202 203 system_scaled = (system_scaled * mult) / div; 204 } 205 account_system_time(tsk, 0, system, system_scaled); 206 207 virt_timer_forward(system); 208 } 209 EXPORT_SYMBOL_GPL(vtime_account_irq_enter); 210 211 void vtime_account_system(struct task_struct *tsk) 212 __attribute__((alias("vtime_account_irq_enter"))); 213 EXPORT_SYMBOL_GPL(vtime_account_system); 214 215 /* 216 * Sorted add to a list. List is linear searched until first bigger 217 * element is found. 218 */ 219 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head) 220 { 221 struct vtimer_list *tmp; 222 223 list_for_each_entry(tmp, head, entry) { 224 if (tmp->expires > timer->expires) { 225 list_add_tail(&timer->entry, &tmp->entry); 226 return; 227 } 228 } 229 list_add_tail(&timer->entry, head); 230 } 231 232 /* 233 * Handler for expired virtual CPU timer. 234 */ 235 static void virt_timer_expire(void) 236 { 237 struct vtimer_list *timer, *tmp; 238 unsigned long elapsed; 239 LIST_HEAD(cb_list); 240 241 /* walk timer list, fire all expired timers */ 242 spin_lock(&virt_timer_lock); 243 elapsed = atomic64_read(&virt_timer_elapsed); 244 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) { 245 if (timer->expires < elapsed) 246 /* move expired timer to the callback queue */ 247 list_move_tail(&timer->entry, &cb_list); 248 else 249 timer->expires -= elapsed; 250 } 251 if (!list_empty(&virt_timer_list)) { 252 timer = list_first_entry(&virt_timer_list, 253 struct vtimer_list, entry); 254 atomic64_set(&virt_timer_current, timer->expires); 255 } 256 atomic64_sub(elapsed, &virt_timer_elapsed); 257 spin_unlock(&virt_timer_lock); 258 259 /* Do callbacks and recharge periodic timers */ 260 list_for_each_entry_safe(timer, tmp, &cb_list, entry) { 261 list_del_init(&timer->entry); 262 timer->function(timer->data); 263 if (timer->interval) { 264 /* Recharge interval timer */ 265 timer->expires = timer->interval + 266 atomic64_read(&virt_timer_elapsed); 267 spin_lock(&virt_timer_lock); 268 list_add_sorted(timer, &virt_timer_list); 269 spin_unlock(&virt_timer_lock); 270 } 271 } 272 } 273 274 void init_virt_timer(struct vtimer_list *timer) 275 { 276 timer->function = NULL; 277 INIT_LIST_HEAD(&timer->entry); 278 } 279 EXPORT_SYMBOL(init_virt_timer); 280 281 static inline int vtimer_pending(struct vtimer_list *timer) 282 { 283 return !list_empty(&timer->entry); 284 } 285 286 static void internal_add_vtimer(struct vtimer_list *timer) 287 { 288 if (list_empty(&virt_timer_list)) { 289 /* First timer, just program it. */ 290 atomic64_set(&virt_timer_current, timer->expires); 291 atomic64_set(&virt_timer_elapsed, 0); 292 list_add(&timer->entry, &virt_timer_list); 293 } else { 294 /* Update timer against current base. */ 295 timer->expires += atomic64_read(&virt_timer_elapsed); 296 if (likely((s64) timer->expires < 297 (s64) atomic64_read(&virt_timer_current))) 298 /* The new timer expires before the current timer. */ 299 atomic64_set(&virt_timer_current, timer->expires); 300 /* Insert new timer into the list. */ 301 list_add_sorted(timer, &virt_timer_list); 302 } 303 } 304 305 static void __add_vtimer(struct vtimer_list *timer, int periodic) 306 { 307 unsigned long flags; 308 309 timer->interval = periodic ? timer->expires : 0; 310 spin_lock_irqsave(&virt_timer_lock, flags); 311 internal_add_vtimer(timer); 312 spin_unlock_irqrestore(&virt_timer_lock, flags); 313 } 314 315 /* 316 * add_virt_timer - add an oneshot virtual CPU timer 317 */ 318 void add_virt_timer(struct vtimer_list *timer) 319 { 320 __add_vtimer(timer, 0); 321 } 322 EXPORT_SYMBOL(add_virt_timer); 323 324 /* 325 * add_virt_timer_int - add an interval virtual CPU timer 326 */ 327 void add_virt_timer_periodic(struct vtimer_list *timer) 328 { 329 __add_vtimer(timer, 1); 330 } 331 EXPORT_SYMBOL(add_virt_timer_periodic); 332 333 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic) 334 { 335 unsigned long flags; 336 int rc; 337 338 BUG_ON(!timer->function); 339 340 if (timer->expires == expires && vtimer_pending(timer)) 341 return 1; 342 spin_lock_irqsave(&virt_timer_lock, flags); 343 rc = vtimer_pending(timer); 344 if (rc) 345 list_del_init(&timer->entry); 346 timer->interval = periodic ? expires : 0; 347 timer->expires = expires; 348 internal_add_vtimer(timer); 349 spin_unlock_irqrestore(&virt_timer_lock, flags); 350 return rc; 351 } 352 353 /* 354 * returns whether it has modified a pending timer (1) or not (0) 355 */ 356 int mod_virt_timer(struct vtimer_list *timer, u64 expires) 357 { 358 return __mod_vtimer(timer, expires, 0); 359 } 360 EXPORT_SYMBOL(mod_virt_timer); 361 362 /* 363 * returns whether it has modified a pending timer (1) or not (0) 364 */ 365 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires) 366 { 367 return __mod_vtimer(timer, expires, 1); 368 } 369 EXPORT_SYMBOL(mod_virt_timer_periodic); 370 371 /* 372 * Delete a virtual timer. 373 * 374 * returns whether the deleted timer was pending (1) or not (0) 375 */ 376 int del_virt_timer(struct vtimer_list *timer) 377 { 378 unsigned long flags; 379 380 if (!vtimer_pending(timer)) 381 return 0; 382 spin_lock_irqsave(&virt_timer_lock, flags); 383 list_del_init(&timer->entry); 384 spin_unlock_irqrestore(&virt_timer_lock, flags); 385 return 1; 386 } 387 EXPORT_SYMBOL(del_virt_timer); 388 389 /* 390 * Start the virtual CPU timer on the current CPU. 391 */ 392 void vtime_init(void) 393 { 394 /* set initial cpu timer */ 395 set_vtimer(VTIMER_MAX_SLICE); 396 /* Setup initial MT scaling values */ 397 if (smp_cpu_mtid) { 398 __this_cpu_write(mt_scaling_jiffies, jiffies); 399 __this_cpu_write(mt_scaling_mult, 1); 400 __this_cpu_write(mt_scaling_div, 1); 401 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles)); 402 } 403 } 404