- Move rusage from being per-process in struct pstats to per-thread in

   td_ru.  This removes the requirement for per-process synchronization in
   statclock() and mi_switch().  This was previously supported by
   sched_lock which is going away.  All modifications to rusage are now
   done in the context of the owning thread.  reads proceed without locks.
 - Aggregate exiting threads rusage in thread_exit() such that the exiting
   thread's rusage is not lost.
 - Provide a new routine, rufetch() to fetch an aggregate of all rusage
   structures from all threads in a process.  This routine must be used
   in any place requiring a rusage from a process prior to it's exit.  The
   exited process's rusage is still available via p_ru.
 - Aggregate tick statistics only on demand via rufetch() or when a thread
   exits.  Tick statistics are kept in the thread and protected by sched_lock
   until it exits.

Initial patch by:	attilio
Reviewed by:		attilio, bde (some objections), arch (mostly silent)

1 files changed, 5 insertions, 27 deletions

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index d61dddf..b75dcf2 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -401,40 +401,18 @@ mi_switch(int flags, struct thread *newtd)
 	}
 
 	if (flags & SW_VOL)
-		p->p_stats->p_ru.ru_nvcsw++;
+		td->td_ru.ru_nvcsw++;
 	else
-		p->p_stats->p_ru.ru_nivcsw++;
-
+		td->td_ru.ru_nivcsw++;
 	/*
 	 * Compute the amount of time during which the current
-	 * process was running, and add that to its total so far.
+	 * thread was running, and add that to its total so far.
 	 */
 	new_switchtime = cpu_ticks();
-	p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime));
-	p->p_rux.rux_uticks += td->td_uticks;
-	td->td_uticks = 0;
-	p->p_rux.rux_iticks += td->td_iticks;
-	td->td_iticks = 0;
-	p->p_rux.rux_sticks += td->td_sticks;
-	td->td_sticks = 0;
-
+	td->td_runtime += new_switchtime - PCPU_GET(switchtime);
+	PCPU_SET(switchtime, new_switchtime);
 	td->td_generation++;	/* bump preempt-detect counter */
-
-	/*
-	 * Check if the process exceeds its cpu resource allocation.  If
-	 * it reaches the max, arrange to kill the process in ast().
-	 */
-	if (p->p_cpulimit != RLIM_INFINITY &&
-	    p->p_rux.rux_runtime >= p->p_cpulimit * cpu_tickrate()) {
-		p->p_sflag |= PS_XCPU;
-		td->td_flags |= TDF_ASTPENDING;
-	}
-
-	/*
-	 * Finish up stats for outgoing thread.
-	 */
 	cnt.v_swtch++;
-	PCPU_SET(switchtime, new_switchtime);
 	PCPU_SET(switchticks, ticks);
 	CTR4(KTR_PROC, "mi_switch: old thread %ld (kse %p, pid %ld, %s)",
 	    td->td_tid, td->td_sched, p->p_pid, p->p_comm);