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Date:      Tue, 3 Jan 2012 21:03:28 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r229429 - head/sys/kern
Message-ID:  <201201032103.q03L3SSQ043069@svn.freebsd.org>
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Author: jhb
Date: Tue Jan  3 21:03:28 2012
New Revision: 229429
URL: http://svn.freebsd.org/changeset/base/229429

Log:
  Some small fixes to CPU accounting for threads:
  - 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

Modified:
  head/sys/kern/kern_thread.c
  head/sys/kern/sched_4bsd.c
  head/sys/kern/sched_ule.c

Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c	Tue Jan  3 21:03:20 2012	(r229428)
+++ head/sys/kern/kern_thread.c	Tue Jan  3 21:03:28 2012	(r229429)
@@ -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;

Modified: head/sys/kern/sched_4bsd.c
==============================================================================
--- head/sys/kern/sched_4bsd.c	Tue Jan  3 21:03:20 2012	(r229428)
+++ head/sys/kern/sched_4bsd.c	Tue Jan  3 21:03:28 2012	(r229429)
@@ -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 */
 }
 

Modified: head/sys/kern/sched_ule.c
==============================================================================
--- head/sys/kern/sched_ule.c	Tue Jan  3 21:03:20 2012	(r229428)
+++ head/sys/kern/sched_ule.c	Tue Jan  3 21:03:28 2012	(r229429)
@@ -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 */
 }

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