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schedule_timeout(): give a chance to other process in spin sleep if CPU core is oversubscribed

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This commit is contained in:
Balazs Gerofi
2015-07-28 20:06:56 +09:00
parent 9b1e691588
commit 4e58d08f5c
2 changed files with 68 additions and 22 deletions
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86
kernel/timer.c
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@ -58,22 +58,24 @@ uint64_t schedule_timeout(uint64_t timeout)
struct waitq_entry my_wait;
struct timer my_timer;
struct process *proc = cpu_local_var(current);
int irqstate;
int spin_sleep;
ihk_mc_spinlock_lock_noirq(&proc->spin_sleep_lock);
irqstate = ihk_mc_spinlock_lock(&proc->spin_sleep_lock);
dkprintf("schedule_timeout() spin sleep timeout: %lu\n", timeout);
proc->spin_sleep = 1;
ihk_mc_spinlock_unlock_noirq(&proc->spin_sleep_lock);
spin_sleep = ++proc->spin_sleep;
ihk_mc_spinlock_unlock(&proc->spin_sleep_lock, irqstate);
/* Spin sleep.. */
for (;;) {
uint64_t t_s = rdtsc();
uint64_t t_e;
int spin_over = 0;
ihk_mc_spinlock_lock_noirq(&proc->spin_sleep_lock);
irqstate = ihk_mc_spinlock_lock(&proc->spin_sleep_lock);
/* Woken up by someone? */
if (!proc->spin_sleep) {
if (proc->spin_sleep < 1) {
t_e = rdtsc();
spin_over = 1;
@ -85,25 +87,69 @@ uint64_t schedule_timeout(uint64_t timeout)
}
}
ihk_mc_spinlock_unlock_noirq(&proc->spin_sleep_lock);
ihk_mc_spinlock_unlock(&proc->spin_sleep_lock, irqstate);
t_s = rdtsc();
if (!spin_over) {
t_s = rdtsc();
int need_schedule;
struct cpu_local_var *v = get_this_cpu_local_var();
int irqstate = ihk_mc_spinlock_lock(&(v->runq_lock));
need_schedule = v->runq_len > 1 ? 1 : 0;
ihk_mc_spinlock_unlock(&(v->runq_lock), irqstate);
/* Give a chance to another process (if any) in case the core is
* oversubscribed, but make sure we will be re-scheduled */
if (need_schedule) {
xchg4(&(cpu_local_var(current)->ftn->status), PS_RUNNING);
schedule();
xchg4(&(cpu_local_var(current)->ftn->status),
PS_INTERRUPTIBLE);
}
else {
/* Spin wait */
while ((rdtsc() - t_s) < LOOP_TIMEOUT) {
cpu_pause();
}
if (timeout < LOOP_TIMEOUT) {
timeout = 0;
spin_over = 1;
}
else {
timeout -= LOOP_TIMEOUT;
}
}
}
while ((rdtsc() - t_s) < LOOP_TIMEOUT) {
cpu_pause();
}
if (timeout < LOOP_TIMEOUT) {
timeout = 0;
spin_over = 1;
}
else {
timeout -= LOOP_TIMEOUT;
}
if (spin_over) {
dkprintf("schedule_timeout() spin woken up, timeout: %lu\n",
timeout);
/* Give a chance to another process (if any) in case we timed out,
* but make sure we will be re-scheduled */
if (timeout == 0) {
int need_schedule;
struct cpu_local_var *v = get_this_cpu_local_var();
int irqstate =
ihk_mc_spinlock_lock(&(v->runq_lock));
need_schedule = v->runq_len > 1 ? 1 : 0;
ihk_mc_spinlock_unlock(&(v->runq_lock), irqstate);
if (need_schedule) {
xchg4(&(cpu_local_var(current)->ftn->status), PS_RUNNING);
schedule();
xchg4(&(cpu_local_var(current)->ftn->status),
PS_INTERRUPTIBLE);
}
}
irqstate = ihk_mc_spinlock_lock(&proc->spin_sleep_lock);
if (spin_sleep == proc->spin_sleep) {
--proc->spin_sleep;
}
ihk_mc_spinlock_unlock(&proc->spin_sleep_lock, irqstate);
return timeout;
}
}