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Some small fixes to CPU accounting for threads:

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- Only initialize the per-cpu switchticks and switchtime in sched_throw()
  for the very first context switch on APs during boot.  This avoids a
  small gap between the middle of thread_exit() and sched_throw() where
  time is not accounted to any thread.
- In thread_exit(), update the timestamp bookkeeping to track the changes
  to mi_switch() introduced by td_rux so that the code once again matches
  the comment claiming it is mimicing mi_switch().  Specifically, only
  update the per-thread stats directly and depend on ruxagg() to update
  p_rux rather than adjusting p_rux directly.  While here, move the
  timestamp bookkeeping as late in the function as possible.

Reviewed by:	bde, kib
MFC after:	1 week
This commit is contained in:
John Baldwin 2012-01-03 21:03:28 +00:00
parent 48a1e3f624
commit 7e3a96ea37
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=229429
3 changed files with 19 additions and 14 deletions
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25
sys/kern/kern_thread.c
View File

@ -381,7 +381,7 @@ thread_free(struct thread *td)
void
thread_exit(void)
{
uint64_t new_switchtime;
uint64_t runtime, new_switchtime;
struct thread *td;
struct thread *td2;
struct proc *p;
@ -410,15 +410,6 @@ thread_exit(void)
*/
cpu_thread_exit(td); /* XXXSMP */
/* Do the same timestamp bookkeeping that mi_switch() would do. */
new_switchtime = cpu_ticks();
p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime));
PCPU_SET(switchtime, new_switchtime);
PCPU_SET(switchticks, ticks);
PCPU_INC(cnt.v_swtch);
/* Save our resource usage in our process. */
td->td_ru.ru_nvcsw++;
rucollect(&p->p_ru, &td->td_ru);
/*
* The last thread is left attached to the process
* So that the whole bundle gets recycled. Skip
@ -467,7 +458,21 @@ thread_exit(void)
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
#endif
PROC_UNLOCK(p);
/* Do the same timestamp bookkeeping that mi_switch() would do. */
new_switchtime = cpu_ticks();
runtime = new_switchtime - PCPU_GET(switchtime);
td->td_runtime += runtime;
td->td_incruntime += runtime;
PCPU_SET(switchtime, new_switchtime);
PCPU_SET(switchticks, ticks);
PCPU_INC(cnt.v_swtch);
/* Save our resource usage in our process. */
td->td_ru.ru_nvcsw++;
ruxagg(p, td);
rucollect(&p->p_ru, &td->td_ru);
thread_lock(td);
PROC_SUNLOCK(p);
td->td_state = TDS_INACTIVE;

4
sys/kern/sched_4bsd.c
View File

@ -1572,14 +1572,14 @@ sched_throw(struct thread *td)
if (td == NULL) {
mtx_lock_spin(&sched_lock);
spinlock_exit();
PCPU_SET(switchtime, cpu_ticks());
PCPU_SET(switchticks, ticks);
} else {
lock_profile_release_lock(&sched_lock.lock_object);
MPASS(td->td_lock == &sched_lock);
}
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
PCPU_SET(switchtime, cpu_ticks());
PCPU_SET(switchticks, ticks);
cpu_throw(td, choosethread()); /* doesn't return */
}

4
sys/kern/sched_ule.c
View File

@ -2587,6 +2587,8 @@ sched_throw(struct thread *td)
/* Correct spinlock nesting and acquire the correct lock. */
TDQ_LOCK(tdq);
spinlock_exit();
PCPU_SET(switchtime, cpu_ticks());
PCPU_SET(switchticks, ticks);
} else {
MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
tdq_load_rem(tdq, td);
@ -2595,8 +2597,6 @@ sched_throw(struct thread *td)
KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
newtd = choosethread();
TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
PCPU_SET(switchtime, cpu_ticks());
PCPU_SET(switchticks, ticks);
cpu_throw(td, newtd); /* doesn't return */
}