aboutsummaryrefslogtreecommitdiff
path: root/kernel/posix-cpu-timers.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/posix-cpu-timers.c')
-rw-r--r--kernel/posix-cpu-timers.c471
1 files changed, 252 insertions, 219 deletions
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index c42a03aef36..dba1c334c3e 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -8,6 +8,99 @@
#include <linux/math64.h>
#include <asm/uaccess.h>
+#ifdef CONFIG_SMP
+/*
+ * Allocate the thread_group_cputime structure appropriately for SMP kernels
+ * and fill in the current values of the fields. Called from copy_signal()
+ * via thread_group_cputime_clone_thread() when adding a second or subsequent
+ * thread to a thread group. Assumes interrupts are enabled when called.
+ */
+int thread_group_cputime_alloc_smp(struct task_struct *tsk)
+{
+ struct signal_struct *sig = tsk->signal;
+ struct task_cputime *cputime;
+
+ /*
+ * If we have multiple threads and we don't already have a
+ * per-CPU task_cputime struct, allocate one and fill it in with
+ * the times accumulated so far.
+ */
+ if (sig->cputime.totals)
+ return 0;
+ cputime = alloc_percpu(struct task_cputime);
+ if (cputime == NULL)
+ return -ENOMEM;
+ read_lock(&tasklist_lock);
+ spin_lock_irq(&tsk->sighand->siglock);
+ if (sig->cputime.totals) {
+ spin_unlock_irq(&tsk->sighand->siglock);
+ read_unlock(&tasklist_lock);
+ free_percpu(cputime);
+ return 0;
+ }
+ sig->cputime.totals = cputime;
+ cputime = per_cpu_ptr(sig->cputime.totals, get_cpu());
+ cputime->utime = tsk->utime;
+ cputime->stime = tsk->stime;
+ cputime->sum_exec_runtime = tsk->se.sum_exec_runtime;
+ put_cpu_no_resched();
+ spin_unlock_irq(&tsk->sighand->siglock);
+ read_unlock(&tasklist_lock);
+ return 0;
+}
+
+/**
+ * thread_group_cputime_smp - Sum the thread group time fields across all CPUs.
+ *
+ * @tsk: The task we use to identify the thread group.
+ * @times: task_cputime structure in which we return the summed fields.
+ *
+ * Walk the list of CPUs to sum the per-CPU time fields in the thread group
+ * time structure.
+ */
+void thread_group_cputime_smp(
+ struct task_struct *tsk,
+ struct task_cputime *times)
+{
+ struct signal_struct *sig;
+ int i;
+ struct task_cputime *tot;
+
+ sig = tsk->signal;
+ if (unlikely(!sig) || !sig->cputime.totals) {
+ times->utime = tsk->utime;
+ times->stime = tsk->stime;
+ times->sum_exec_runtime = tsk->se.sum_exec_runtime;
+ return;
+ }
+ times->stime = times->utime = cputime_zero;
+ times->sum_exec_runtime = 0;
+ for_each_possible_cpu(i) {
+ tot = per_cpu_ptr(tsk->signal->cputime.totals, i);
+ times->utime = cputime_add(times->utime, tot->utime);
+ times->stime = cputime_add(times->stime, tot->stime);
+ times->sum_exec_runtime += tot->sum_exec_runtime;
+ }
+}
+
+#endif /* CONFIG_SMP */
+
+/*
+ * Called after updating RLIMIT_CPU to set timer expiration if necessary.
+ */
+void update_rlimit_cpu(unsigned long rlim_new)
+{
+ cputime_t cputime;
+
+ cputime = secs_to_cputime(rlim_new);
+ if (cputime_eq(current->signal->it_prof_expires, cputime_zero) ||
+ cputime_lt(current->signal->it_prof_expires, cputime)) {
+ spin_lock_irq(&current->sighand->siglock);
+ set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
+ spin_unlock_irq(&current->sighand->siglock);
+ }
+}
+
static int check_clock(const clockid_t which_clock)
{
int error = 0;
@@ -158,10 +251,6 @@ static inline cputime_t virt_ticks(struct task_struct *p)
{
return p->utime;
}
-static inline unsigned long long sched_ns(struct task_struct *p)
-{
- return task_sched_runtime(p);
-}
int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
{
@@ -211,7 +300,7 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
cpu->cpu = virt_ticks(p);
break;
case CPUCLOCK_SCHED:
- cpu->sched = sched_ns(p);
+ cpu->sched = task_sched_runtime(p);
break;
}
return 0;
@@ -226,31 +315,20 @@ static int cpu_clock_sample_group_locked(unsigned int clock_idx,
struct task_struct *p,
union cpu_time_count *cpu)
{
- struct task_struct *t = p;
- switch (clock_idx) {
+ struct task_cputime cputime;
+
+ thread_group_cputime(p, &cputime);
+ switch (clock_idx) {
default:
return -EINVAL;
case CPUCLOCK_PROF:
- cpu->cpu = cputime_add(p->signal->utime, p->signal->stime);
- do {
- cpu->cpu = cputime_add(cpu->cpu, prof_ticks(t));
- t = next_thread(t);
- } while (t != p);
+ cpu->cpu = cputime_add(cputime.utime, cputime.stime);
break;
case CPUCLOCK_VIRT:
- cpu->cpu = p->signal->utime;
- do {
- cpu->cpu = cputime_add(cpu->cpu, virt_ticks(t));
- t = next_thread(t);
- } while (t != p);
+ cpu->cpu = cputime.utime;
break;
case CPUCLOCK_SCHED:
- cpu->sched = p->signal->sum_sched_runtime;
- /* Add in each other live thread. */
- while ((t = next_thread(t)) != p) {
- cpu->sched += t->se.sum_exec_runtime;
- }
- cpu->sched += sched_ns(p);
+ cpu->sched = thread_group_sched_runtime(p);
break;
}
return 0;
@@ -471,80 +549,11 @@ void posix_cpu_timers_exit(struct task_struct *tsk)
}
void posix_cpu_timers_exit_group(struct task_struct *tsk)
{
- cleanup_timers(tsk->signal->cpu_timers,
- cputime_add(tsk->utime, tsk->signal->utime),
- cputime_add(tsk->stime, tsk->signal->stime),
- tsk->se.sum_exec_runtime + tsk->signal->sum_sched_runtime);
-}
-
-
-/*
- * Set the expiry times of all the threads in the process so one of them
- * will go off before the process cumulative expiry total is reached.
- */
-static void process_timer_rebalance(struct task_struct *p,
- unsigned int clock_idx,
- union cpu_time_count expires,
- union cpu_time_count val)
-{
- cputime_t ticks, left;
- unsigned long long ns, nsleft;
- struct task_struct *t = p;
- unsigned int nthreads = atomic_read(&p->signal->live);
-
- if (!nthreads)
- return;
+ struct task_cputime cputime;
- switch (clock_idx) {
- default:
- BUG();
- break;
- case CPUCLOCK_PROF:
- left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
- nthreads);
- do {
- if (likely(!(t->flags & PF_EXITING))) {
- ticks = cputime_add(prof_ticks(t), left);
- if (cputime_eq(t->it_prof_expires,
- cputime_zero) ||
- cputime_gt(t->it_prof_expires, ticks)) {
- t->it_prof_expires = ticks;
- }
- }
- t = next_thread(t);
- } while (t != p);
- break;
- case CPUCLOCK_VIRT:
- left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
- nthreads);
- do {
- if (likely(!(t->flags & PF_EXITING))) {
- ticks = cputime_add(virt_ticks(t), left);
- if (cputime_eq(t->it_virt_expires,
- cputime_zero) ||
- cputime_gt(t->it_virt_expires, ticks)) {
- t->it_virt_expires = ticks;
- }
- }
- t = next_thread(t);
- } while (t != p);
- break;
- case CPUCLOCK_SCHED:
- nsleft = expires.sched - val.sched;
- do_div(nsleft, nthreads);
- nsleft = max_t(unsigned long long, nsleft, 1);
- do {
- if (likely(!(t->flags & PF_EXITING))) {
- ns = t->se.sum_exec_runtime + nsleft;
- if (t->it_sched_expires == 0 ||
- t->it_sched_expires > ns) {
- t->it_sched_expires = ns;
- }
- }
- t = next_thread(t);
- } while (t != p);
- break;
- }
+ thread_group_cputime(tsk, &cputime);
+ cleanup_timers(tsk->signal->cpu_timers,
+ cputime.utime, cputime.stime, cputime.sum_exec_runtime);
}
static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
@@ -608,29 +617,32 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
default:
BUG();
case CPUCLOCK_PROF:
- if (cputime_eq(p->it_prof_expires,
+ if (cputime_eq(p->cputime_expires.prof_exp,
cputime_zero) ||
- cputime_gt(p->it_prof_expires,
+ cputime_gt(p->cputime_expires.prof_exp,
nt->expires.cpu))
- p->it_prof_expires = nt->expires.cpu;
+ p->cputime_expires.prof_exp =
+ nt->expires.cpu;
break;
case CPUCLOCK_VIRT:
- if (cputime_eq(p->it_virt_expires,
+ if (cputime_eq(p->cputime_expires.virt_exp,
cputime_zero) ||
- cputime_gt(p->it_virt_expires,
+ cputime_gt(p->cputime_expires.virt_exp,
nt->expires.cpu))
- p->it_virt_expires = nt->expires.cpu;
+ p->cputime_expires.virt_exp =
+ nt->expires.cpu;
break;
case CPUCLOCK_SCHED:
- if (p->it_sched_expires == 0 ||
- p->it_sched_expires > nt->expires.sched)
- p->it_sched_expires = nt->expires.sched;
+ if (p->cputime_expires.sched_exp == 0 ||
+ p->cputime_expires.sched_exp >
+ nt->expires.sched)
+ p->cputime_expires.sched_exp =
+ nt->expires.sched;
break;
}
} else {
/*
- * For a process timer, we must balance
- * all the live threads' expirations.
+ * For a process timer, set the cached expiration time.
*/
switch (CPUCLOCK_WHICH(timer->it_clock)) {
default:
@@ -641,7 +653,9 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
cputime_lt(p->signal->it_virt_expires,
timer->it.cpu.expires.cpu))
break;
- goto rebalance;
+ p->signal->cputime_expires.virt_exp =
+ timer->it.cpu.expires.cpu;
+ break;
case CPUCLOCK_PROF:
if (!cputime_eq(p->signal->it_prof_expires,
cputime_zero) &&
@@ -652,13 +666,12 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
if (i != RLIM_INFINITY &&
i <= cputime_to_secs(timer->it.cpu.expires.cpu))
break;
- goto rebalance;
+ p->signal->cputime_expires.prof_exp =
+ timer->it.cpu.expires.cpu;
+ break;
case CPUCLOCK_SCHED:
- rebalance:
- process_timer_rebalance(
- timer->it.cpu.task,
- CPUCLOCK_WHICH(timer->it_clock),
- timer->it.cpu.expires, now);
+ p->signal->cputime_expires.sched_exp =
+ timer->it.cpu.expires.sched;
break;
}
}
@@ -969,13 +982,13 @@ static void check_thread_timers(struct task_struct *tsk,
struct signal_struct *const sig = tsk->signal;
maxfire = 20;
- tsk->it_prof_expires = cputime_zero;
+ tsk->cputime_expires.prof_exp = cputime_zero;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list,
entry);
if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
- tsk->it_prof_expires = t->expires.cpu;
+ tsk->cputime_expires.prof_exp = t->expires.cpu;
break;
}
t->firing = 1;
@@ -984,13 +997,13 @@ static void check_thread_timers(struct task_struct *tsk,
++timers;
maxfire = 20;
- tsk->it_virt_expires = cputime_zero;
+ tsk->cputime_expires.virt_exp = cputime_zero;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list,
entry);
if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
- tsk->it_virt_expires = t->expires.cpu;
+ tsk->cputime_expires.virt_exp = t->expires.cpu;
break;
}
t->firing = 1;
@@ -999,13 +1012,13 @@ static void check_thread_timers(struct task_struct *tsk,
++timers;
maxfire = 20;
- tsk->it_sched_expires = 0;
+ tsk->cputime_expires.sched_exp = 0;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_first_entry(timers,
struct cpu_timer_list,
entry);
if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
- tsk->it_sched_expires = t->expires.sched;
+ tsk->cputime_expires.sched_exp = t->expires.sched;
break;
}
t->firing = 1;
@@ -1055,10 +1068,10 @@ static void check_process_timers(struct task_struct *tsk,
{
int maxfire;
struct signal_struct *const sig = tsk->signal;
- cputime_t utime, stime, ptime, virt_expires, prof_expires;
+ cputime_t utime, ptime, virt_expires, prof_expires;
unsigned long long sum_sched_runtime, sched_expires;
- struct task_struct *t;
struct list_head *timers = sig->cpu_timers;
+ struct task_cputime cputime;
/*
* Don't sample the current process CPU clocks if there are no timers.
@@ -1074,18 +1087,10 @@ static void check_process_timers(struct task_struct *tsk,
/*
* Collect the current process totals.
*/
- utime = sig->utime;
- stime = sig->stime;
- sum_sched_runtime = sig->sum_sched_runtime;
- t = tsk;
- do {
- utime = cputime_add(utime, t->utime);
- stime = cputime_add(stime, t->stime);
- sum_sched_runtime += t->se.sum_exec_runtime;
- t = next_thread(t);
- } while (t != tsk);
- ptime = cputime_add(utime, stime);
-
+ thread_group_cputime(tsk, &cputime);
+ utime = cputime.utime;
+ ptime = cputime_add(utime, cputime.stime);
+ sum_sched_runtime = cputime.sum_exec_runtime;
maxfire = 20;
prof_expires = cputime_zero;
while (!list_empty(timers)) {
@@ -1193,60 +1198,18 @@ static void check_process_timers(struct task_struct *tsk,
}
}
- if (!cputime_eq(prof_expires, cputime_zero) ||
- !cputime_eq(virt_expires, cputime_zero) ||
- sched_expires != 0) {
- /*
- * Rebalance the threads' expiry times for the remaining
- * process CPU timers.
- */
-
- cputime_t prof_left, virt_left, ticks;
- unsigned long long sched_left, sched;
- const unsigned int nthreads = atomic_read(&sig->live);
-
- if (!nthreads)
- return;
-
- prof_left = cputime_sub(prof_expires, utime);
- prof_left = cputime_sub(prof_left, stime);
- prof_left = cputime_div_non_zero(prof_left, nthreads);
- virt_left = cputime_sub(virt_expires, utime);
- virt_left = cputime_div_non_zero(virt_left, nthreads);
- if (sched_expires) {
- sched_left = sched_expires - sum_sched_runtime;
- do_div(sched_left, nthreads);
- sched_left = max_t(unsigned long long, sched_left, 1);
- } else {
- sched_left = 0;
- }
- t = tsk;
- do {
- if (unlikely(t->flags & PF_EXITING))
- continue;
-
- ticks = cputime_add(cputime_add(t->utime, t->stime),
- prof_left);
- if (!cputime_eq(prof_expires, cputime_zero) &&
- (cputime_eq(t->it_prof_expires, cputime_zero) ||
- cputime_gt(t->it_prof_expires, ticks))) {
- t->it_prof_expires = ticks;
- }
-
- ticks = cputime_add(t->utime, virt_left);
- if (!cputime_eq(virt_expires, cputime_zero) &&
- (cputime_eq(t->it_virt_expires, cputime_zero) ||
- cputime_gt(t->it_virt_expires, ticks))) {
- t->it_virt_expires = ticks;
- }
-
- sched = t->se.sum_exec_runtime + sched_left;
- if (sched_expires && (t->it_sched_expires == 0 ||
- t->it_sched_expires > sched)) {
- t->it_sched_expires = sched;
- }
- } while ((t = next_thread(t)) != tsk);
- }
+ if (!cputime_eq(prof_expires, cputime_zero) &&
+ (cputime_eq(sig->cputime_expires.prof_exp, cputime_zero) ||
+ cputime_gt(sig->cputime_expires.prof_exp, prof_expires)))
+ sig->cputime_expires.prof_exp = prof_expires;
+ if (!cputime_eq(virt_expires, cputime_zero) &&
+ (cputime_eq(sig->cputime_expires.virt_exp, cputime_zero) ||
+ cputime_gt(sig->cputime_expires.virt_exp, virt_expires)))
+ sig->cputime_expires.virt_exp = virt_expires;
+ if (sched_expires != 0 &&
+ (sig->cputime_expires.sched_exp == 0 ||
+ sig->cputime_expires.sched_exp > sched_expires))
+ sig->cputime_expires.sched_exp = sched_expires;
}
/*
@@ -1314,6 +1277,78 @@ out:
++timer->it_requeue_pending;
}
+/**
+ * task_cputime_zero - Check a task_cputime struct for all zero fields.
+ *
+ * @cputime: The struct to compare.
+ *
+ * Checks @cputime to see if all fields are zero. Returns true if all fields
+ * are zero, false if any field is nonzero.
+ */
+static inline int task_cputime_zero(const struct task_cputime *cputime)
+{
+ if (cputime_eq(cputime->utime, cputime_zero) &&
+ cputime_eq(cputime->stime, cputime_zero) &&
+ cputime->sum_exec_runtime == 0)
+ return 1;
+ return 0;
+}
+
+/**
+ * task_cputime_expired - Compare two task_cputime entities.
+ *
+ * @sample: The task_cputime structure to be checked for expiration.
+ * @expires: Expiration times, against which @sample will be checked.
+ *
+ * Checks @sample against @expires to see if any field of @sample has expired.
+ * Returns true if any field of the former is greater than the corresponding
+ * field of the latter if the latter field is set. Otherwise returns false.
+ */
+static inline int task_cputime_expired(const struct task_cputime *sample,
+ const struct task_cputime *expires)
+{
+ if (!cputime_eq(expires->utime, cputime_zero) &&
+ cputime_ge(sample->utime, expires->utime))
+ return 1;
+ if (!cputime_eq(expires->stime, cputime_zero) &&
+ cputime_ge(cputime_add(sample->utime, sample->stime),
+ expires->stime))
+ return 1;
+ if (expires->sum_exec_runtime != 0 &&
+ sample->sum_exec_runtime >= expires->sum_exec_runtime)
+ return 1;
+ return 0;
+}
+
+/**
+ * fastpath_timer_check - POSIX CPU timers fast path.
+ *
+ * @tsk: The task (thread) being checked.
+ * @sig: The signal pointer for that task.
+ *
+ * If there are no timers set return false. Otherwise snapshot the task and
+ * thread group timers, then compare them with the corresponding expiration
+ # times. Returns true if a timer has expired, else returns false.
+ */
+static inline int fastpath_timer_check(struct task_struct *tsk,
+ struct signal_struct *sig)
+{
+ struct task_cputime task_sample = {
+ .utime = tsk->utime,
+ .stime = tsk->stime,
+ .sum_exec_runtime = tsk->se.sum_exec_runtime
+ };
+ struct task_cputime group_sample;
+
+ if (task_cputime_zero(&tsk->cputime_expires) &&
+ task_cputime_zero(&sig->cputime_expires))
+ return 0;
+ if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
+ return 1;
+ thread_group_cputime(tsk, &group_sample);
+ return task_cputime_expired(&group_sample, &sig->cputime_expires);
+}
+
/*
* This is called from the timer interrupt handler. The irq handler has
* already updated our counts. We need to check if any timers fire now.
@@ -1323,30 +1358,29 @@ void run_posix_cpu_timers(struct task_struct *tsk)
{
LIST_HEAD(firing);
struct k_itimer *timer, *next;
+ struct signal_struct *sig;
+ struct sighand_struct *sighand;
+ unsigned long flags;
BUG_ON(!irqs_disabled());
-#define UNEXPIRED(clock) \
- (cputime_eq(tsk->it_##clock##_expires, cputime_zero) || \
- cputime_lt(clock##_ticks(tsk), tsk->it_##clock##_expires))
-
- if (UNEXPIRED(prof) && UNEXPIRED(virt) &&
- (tsk->it_sched_expires == 0 ||
- tsk->se.sum_exec_runtime < tsk->it_sched_expires))
- return;
-
-#undef UNEXPIRED
-
+ /* Pick up tsk->signal and make sure it's valid. */
+ sig = tsk->signal;
/*
- * Double-check with locks held.
+ * The fast path checks that there are no expired thread or thread
+ * group timers. If that's so, just return. Also check that
+ * tsk->signal is non-NULL; this probably can't happen but cover the
+ * possibility anyway.
*/
- read_lock(&tasklist_lock);
- if (likely(tsk->signal != NULL)) {
- spin_lock(&tsk->sighand->siglock);
-
+ if (unlikely(!sig) || !fastpath_timer_check(tsk, sig)) {
+ return;
+ }
+ sighand = lock_task_sighand(tsk, &flags);
+ if (likely(sighand)) {
/*
- * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
- * all the timers that are firing, and put them on the firing list.
+ * Here we take off tsk->signal->cpu_timers[N] and
+ * tsk->cpu_timers[N] all the timers that are firing, and
+ * put them on the firing list.
*/
check_thread_timers(tsk, &firing);
check_process_timers(tsk, &firing);
@@ -1359,9 +1393,8 @@ void run_posix_cpu_timers(struct task_struct *tsk)
* that gets the timer lock before we do will give it up and
* spin until we've taken care of that timer below.
*/
- spin_unlock(&tsk->sighand->siglock);
}
- read_unlock(&tasklist_lock);
+ unlock_task_sighand(tsk, &flags);
/*
* Now that all the timers on our list have the firing flag,
@@ -1389,10 +1422,9 @@ void run_posix_cpu_timers(struct task_struct *tsk)
/*
* Set one of the process-wide special case CPU timers.
- * The tasklist_lock and tsk->sighand->siglock must be held by the caller.
- * The oldval argument is null for the RLIMIT_CPU timer, where *newval is
- * absolute; non-null for ITIMER_*, where *newval is relative and we update
- * it to be absolute, *oldval is absolute and we update it to be relative.
+ * The tsk->sighand->siglock must be held by the caller.
+ * The *newval argument is relative and we update it to be absolute, *oldval
+ * is absolute and we update it to be relative.
*/
void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
cputime_t *newval, cputime_t *oldval)
@@ -1435,13 +1467,14 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
cputime_ge(list_first_entry(head,
struct cpu_timer_list, entry)->expires.cpu,
*newval)) {
- /*
- * Rejigger each thread's expiry time so that one will
- * notice before we hit the process-cumulative expiry time.
- */
- union cpu_time_count expires = { .sched = 0 };
- expires.cpu = *newval;
- process_timer_rebalance(tsk, clock_idx, expires, now);
+ switch (clock_idx) {
+ case CPUCLOCK_PROF:
+ tsk->signal->cputime_expires.prof_exp = *newval;
+ break;
+ case CPUCLOCK_VIRT:
+ tsk->signal->cputime_expires.virt_exp = *newval;
+ break;
+ }
}
}
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-12-02 06:53:55 +0000