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posix-cpu-timers: Switch thread group sampling to array

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That allows more simplifications in various places.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192921.988426956@linutronix.de
This commit is contained in:
Thomas Gleixner 2019-08-21 21:09:16 +02:00
parent 87dc64480f
commit b7be4ef136
3 changed files with 48 additions and 67 deletions
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2
include/linux/sched/cputime.h
View File

@ -61,7 +61,7 @@ extern void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
* Thread group CPU time accounting.
*/
void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
void thread_group_sample_cputime(struct task_struct *tsk, struct task_cputime *times);
void thread_group_sample_cputime(struct task_struct *tsk, u64 *samples);
/*
* The following are functions that support scheduler-internal time accounting.

11
kernel/time/itimer.c
View File

@ -55,15 +55,10 @@ static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
val = it->expires;
interval = it->incr;
if (val) {
struct task_cputime cputime;
u64 t;
u64 t, samples[CPUCLOCK_MAX];
thread_group_sample_cputime(tsk, &cputime);
if (clock_id == CPUCLOCK_PROF)
t = cputime.utime + cputime.stime;
else
/* CPUCLOCK_VIRT */
t = cputime.utime;
thread_group_sample_cputime(tsk, samples);
t = samples[clock_id];
if (val < t)
/* about to fire */

102
kernel/time/posix-cpu-timers.c
View File

@ -225,22 +225,14 @@ retry:
}
}
static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum)
static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic,
struct task_cputime *sum)
{
__update_gt_cputime(&cputime_atomic->utime, sum->utime);
__update_gt_cputime(&cputime_atomic->stime, sum->stime);
__update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
}
/* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */
static inline void sample_cputime_atomic(struct task_cputime *times,
struct task_cputime_atomic *atomic_times)
{
times->utime = atomic64_read(&atomic_times->utime);
times->stime = atomic64_read(&atomic_times->stime);
times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
}
/**
* thread_group_sample_cputime - Sample cputime for a given task
* @tsk: Task for which cputime needs to be started
@ -252,20 +244,19 @@ static inline void sample_cputime_atomic(struct task_cputime *times,
*
* Updates @times with an uptodate sample of the thread group cputimes.
*/
void thread_group_sample_cputime(struct task_struct *tsk,
struct task_cputime *times)
void thread_group_sample_cputime(struct task_struct *tsk, u64 *samples)
{
struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
WARN_ON_ONCE(!cputimer->running);
sample_cputime_atomic(times, &cputimer->cputime_atomic);
proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
}
/**
* thread_group_start_cputime - Start cputime and return a sample
* @tsk: Task for which cputime needs to be started
* @iimes: Storage for time samples
* @samples: Storage for time samples
*
* The thread group cputime accouting is avoided when there are no posix
* CPU timers armed. Before starting a timer it's required to check whether
@ -274,14 +265,14 @@ void thread_group_sample_cputime(struct task_struct *tsk,
*
* Updates @times with an uptodate sample of the thread group cputimes.
*/
static void
thread_group_start_cputime(struct task_struct *tsk, struct task_cputime *times)
static void thread_group_start_cputime(struct task_struct *tsk, u64 *samples)
{
struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
struct task_cputime sum;
/* Check if cputimer isn't running. This is accessed without locking. */
if (!READ_ONCE(cputimer->running)) {
struct task_cputime sum;
/*
* The POSIX timer interface allows for absolute time expiry
* values through the TIMER_ABSTIME flag, therefore we have
@ -299,7 +290,15 @@ thread_group_start_cputime(struct task_struct *tsk, struct task_cputime *times)
*/
WRITE_ONCE(cputimer->running, true);
}
sample_cputime_atomic(times, &cputimer->cputime_atomic);
proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
}
static void __thread_group_cputime(struct task_struct *tsk, u64 *samples)
{
struct task_cputime ct;
thread_group_cputime(tsk, &ct);
store_samples(samples, ct.stime, ct.utime, ct.sum_exec_runtime);
}
/*
@ -313,28 +312,18 @@ static u64 cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
bool start)
{
struct thread_group_cputimer *cputimer = &p->signal->cputimer;
struct task_cputime cputime;
u64 samples[CPUCLOCK_MAX];
if (!READ_ONCE(cputimer->running)) {
if (start)
thread_group_start_cputime(p, &cputime);
thread_group_start_cputime(p, samples);
else
thread_group_cputime(p, &cputime);
__thread_group_cputime(p, samples);
} else {
sample_cputime_atomic(&cputime, &cputimer->cputime_atomic);
proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
}
switch (clkid) {
case CPUCLOCK_PROF:
return cputime.utime + cputime.stime;
case CPUCLOCK_VIRT:
return cputime.utime;
case CPUCLOCK_SCHED:
return cputime.sum_exec_runtime;
default:
WARN_ON_ONCE(1);
}
return 0;
return samples[clkid];
}
static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)
@ -889,9 +878,7 @@ static void check_process_timers(struct task_struct *tsk,
{
struct signal_struct *const sig = tsk->signal;
struct posix_cputimer_base *base = sig->posix_cputimers.bases;
u64 utime, ptime, virt_expires, prof_expires;
u64 sum_sched_runtime, sched_expires;
struct task_cputime cputime;
u64 virt_exp, prof_exp, sched_exp, samples[CPUCLOCK_MAX];
unsigned long soft;
/*
@ -911,30 +898,29 @@ static void check_process_timers(struct task_struct *tsk,
* Collect the current process totals. Group accounting is active
* so the sample can be taken directly.
*/
sample_cputime_atomic(&cputime, &sig->cputimer.cputime_atomic);
utime = cputime.utime;
ptime = utime + cputime.stime;
sum_sched_runtime = cputime.sum_exec_runtime;
proc_sample_cputime_atomic(&sig->cputimer.cputime_atomic, samples);
prof_expires = check_timers_list(&base[CPUCLOCK_PROF].cpu_timers,
firing, ptime);
virt_expires = check_timers_list(&base[CPUCLOCK_VIRT].cpu_timers,
firing, utime);
sched_expires = check_timers_list(&base[CPUCLOCK_SCHED].cpu_timers,
firing, sum_sched_runtime);
prof_exp = check_timers_list(&base[CPUCLOCK_PROF].cpu_timers,
firing, samples[CPUCLOCK_PROF]);
virt_exp = check_timers_list(&base[CPUCLOCK_VIRT].cpu_timers,
firing, samples[CPUCLOCK_VIRT]);
sched_exp = check_timers_list(&base[CPUCLOCK_SCHED].cpu_timers,
firing, samples[CPUCLOCK_SCHED]);
/*
* Check for the special case process timers.
*/
check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
SIGPROF);
check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
SIGVTALRM);
check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_exp,
samples[CPUCLOCK_PROF], SIGPROF);
check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_exp,
samples[CPUCLOCK_PROF], SIGVTALRM);
soft = task_rlimit(tsk, RLIMIT_CPU);
if (soft != RLIM_INFINITY) {
unsigned long psecs = div_u64(ptime, NSEC_PER_SEC);
u64 softns, ptime = samples[CPUCLOCK_PROF];
unsigned long hard = task_rlimit_max(tsk, RLIMIT_CPU);
u64 x;
unsigned long psecs = div_u64(ptime, NSEC_PER_SEC);
if (psecs >= hard) {
/*
* At the hard limit, we just die.
@ -961,14 +947,14 @@ static void check_process_timers(struct task_struct *tsk,
sig->rlim[RLIMIT_CPU].rlim_cur = soft;
}
}
x = soft * NSEC_PER_SEC;
if (!prof_expires || x < prof_expires)
prof_expires = x;
softns = soft * NSEC_PER_SEC;
if (!prof_exp || softns < prof_exp)
prof_exp = softns;
}
base[CPUCLOCK_PROF].nextevt = prof_expires;
base[CPUCLOCK_VIRT].nextevt = virt_expires;
base[CPUCLOCK_SCHED].nextevt = sched_expires;
base[CPUCLOCK_PROF].nextevt = prof_exp;
base[CPUCLOCK_VIRT].nextevt = virt_exp;
base[CPUCLOCK_SCHED].nextevt = sched_exp;
if (expiry_cache_is_zero(&sig->posix_cputimers))
stop_process_timers(sig);