- 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, 5 deletions

diff --git a/sys/kern/kern_acct.c b/sys/kern/kern_acct.c
index f1b0b8f2a8df..69a171afa84f 100644
--- a/sys/kern/kern_acct.c
+++ b/sys/kern/kern_acct.c
@@ -337,7 +337,7 @@ acct_process(struct thread *td)
 	struct timeval ut, st, tmp;
 	struct plimit *newlim, *oldlim;
 	struct proc *p;
-	struct rusage *r;
+	struct rusage ru;
 	int t, ret, vfslocked;
 
 	/*
@@ -370,6 +370,7 @@ acct_process(struct thread *td)
 	bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
 
 	/* (2) The amount of user and system time that was used */
+	rufetch(p, &ru);
 	calcru(p, &ut, &st);
 	acct.ac_utime = encode_timeval(ut);
 	acct.ac_stime = encode_timeval(st);
@@ -383,19 +384,18 @@ acct_process(struct thread *td)
 	acct.ac_etime = encode_timeval(tmp);
 
 	/* (4) The average amount of memory used */
-	r = &p->p_stats->p_ru;
 	tmp = ut;
 	timevaladd(&tmp, &st);
 	/* Convert tmp (i.e. u + s) into hz units to match ru_i*. */
 	t = tmp.tv_sec * hz + tmp.tv_usec / tick;
 	if (t)
-		acct.ac_mem = encode_long((r->ru_ixrss + r->ru_idrss +
-		    + r->ru_isrss) / t);
+		acct.ac_mem = encode_long((ru.ru_ixrss + ru.ru_idrss +
+		    + ru.ru_isrss) / t);
 	else
 		acct.ac_mem = 0;
 
 	/* (5) The number of disk I/O operations done */
-	acct.ac_io = encode_long(r->ru_inblock + r->ru_oublock);
+	acct.ac_io = encode_long(ru.ru_inblock + ru.ru_oublock);
 
 	/* (6) The UID and GID of the process */
 	acct.ac_uid = p->p_ucred->cr_ruid;