socsvn commit: r240321 - soc2012/rudot/sys/kern

[rudot at FreeBSD.org]

Author: rudot
Date: Mon Aug 13 12:09:39 2012
New Revision: 240321
URL: http://svnweb.FreeBSD.org/socsvn/?view=rev&rev=240321

Log:
  cosmetic changes - adding some comments, some adjustments to comply with the coding style.

Modified:
  soc2012/rudot/sys/kern/kern_racct.c

Modified: soc2012/rudot/sys/kern/kern_racct.c
==============================================================================
--- soc2012/rudot/sys/kern/kern_racct.c	Mon Aug 13 08:16:30 2012	(r240320)
+++ soc2012/rudot/sys/kern/kern_racct.c	Mon Aug 13 12:09:39 2012	(r240321)
@@ -308,17 +308,21 @@
 	fixpt_t p_pctcpu;
 	struct thread *td;
 
+	/*
+	 * If the process is swapped out, we count its %cpu usage as zero.
+	 * This behaviour is consistent with the userland ps(1) tool.
+	 */
 	if ((p->p_flag & P_INMEM) == 0)
 		return (0);
 	swtime = (ticks - p->p_swtick) / hz;
-	if (swtime < RACCT_PCPU_SECS) {
-		/*
-		 * For short-lived processes, the sched_pctcpu() returns small
-		 * values even for cpu intensive processes. Therefore we use
-		 * our own estimate in this case.
-		 */
-		return (pcpu);	
-	}
+
+	/*
+	 * For short-lived processes, the sched_pctcpu() returns small
+	 * values even for cpu intensive processes. Therefore we use
+	 * our own estimate in this case.
+	 */
+	if (swtime < RACCT_PCPU_SECS)
+		return (pcpu);
 
 	p_pctcpu = 0;
 	FOREACH_THREAD_IN_PROC(p, td) {
@@ -355,9 +359,8 @@
 	}
 
 #ifdef SCHED_4BSD
-	if (swtime <= CCPU_EXP_MAX) {
+	if (swtime <= CCPU_EXP_MAX)
 		return ((100 * p_pctcpu) / (FSCALE - ccpu_exp[swtime]));
-	}
 #endif
 
 	return ((100 * p_pctcpu) / FSCALE);
@@ -462,7 +465,7 @@
 
 /*
  * Increase consumption of 'resource' by 'amount' for 'racct'
- * and all its parents.  Differently from other cases, 'amount' here
+ * and all its parents. Differently from other cases, 'amount' here
  * may be less than zero.
  */
 static void
@@ -480,11 +483,18 @@
 		racct->r_resources[resource] = 0;
 	}
 	
-	if (resource == RACCT_PCTCPU) {
-		if (racct->r_resources[RACCT_PCTCPU] > 100) {
-			racct->r_resources[RACCT_PCTCPU] = 100;
-		}
-	}
+	/*
+	 * There are some cases where the racct %cpu resource would grow
+	 * beyond 100%.
+	 * For example in racct_proc_exit() we add the process %cpu usage
+	 * to the ucred racct containers. If too many processes terminated
+	 * in a short time span, the ucred %cpu resource could grow too much.
+	 * Also, the 4BSD scheduler sometimes returns for a thread more than
+	 * 100% cpu usage. So we set a boundary here to 100%.
+	 */
+	if ((resource == RACCT_PCTCPU) &&
+	    (racct->r_resources[RACCT_PCTCPU] > 100))
+		racct->r_resources[RACCT_PCTCPU] = 100;
 }
 
 static int
@@ -609,9 +619,8 @@
 	if (RACCT_IS_DECAYING(resource)) {
 		decayed_amount = old_amount * RACCT_DECAY_FACTOR / FSCALE;
 		diff_cred = amount - decayed_amount;
-	} else {
+	} else
 		diff_cred = diff_proc;
-	}
 	available = INT64_MAX;
 
 	racct_alloc_resource(p->p_racct, resource, diff_proc);
@@ -650,9 +659,8 @@
 	if (RACCT_IS_DECAYING(resource)) {
 		decayed_amount = old_amount * RACCT_DECAY_FACTOR / FSCALE;
 		diff_cred = amount - decayed_amount;
-	} else {
+	} else
 		diff_cred = diff_proc;
-	}
 #ifdef notyet
 	KASSERT(diff_proc >= 0 || RACCT_CAN_DROP(resource),
 	    ("racct_set: usage of non-droppable resource %d dropping",
@@ -726,7 +734,7 @@
 /*
  * Returns amount of 'resource' the process 'p' can keep allocated.
  * Allocating more than that would be denied, unless the resource
- * is marked undeniable.  Amount of already allocated resource does
+ * is marked undeniable. Amount of already allocated resource does
  * not matter.
  */
 uint64_t
@@ -743,7 +751,7 @@
 /*
  * Returns amount of 'resource' the process 'p' can keep allocated.
  * Allocating more than that would be denied, unless the resource
- * is marked undeniable.  Amount of already allocated resource does
+ * is marked undeniable. Amount of already allocated resource does
  * matter.
  */
 uint64_t
@@ -1059,7 +1067,7 @@
 	int resource;
 	int64_t r_old, r_new;
 
-	resource = *(int *) res;
+	resource = *(int *)res;
 	r_old = racct->r_resources[resource];
 
 	/* If there is nothing to decay, just exit. */
@@ -1130,11 +1138,10 @@
 			mtx_lock(&racct_lock);
 			over_limits = racct_set_check_locked(p, RACCT_PCTCPU,
 			    pct);
-			if (over_limits) {
+			if (over_limits)
 				racct_proc_disable(p);
-			} else if (racct_proc_disabled(p)) {
+			else if (racct_proc_disabled(p))
 				racct_proc_enable(p);
-			}
 			racct_set_locked(p, RACCT_CPU, runtime);
 			racct_set_locked(p, RACCT_WALLCLOCK,
 			    (uint64_t)wallclock.tv_sec * 1000000 +