Re: v2.6.21.4-rt11

[Christoph Lameter <clameter@sgi.com>]

On Mon, 18 Jun 2007, Siddha, Suresh B wrote:

> > +		if (time_after(next_balance,
> > +			  sd->last_balance + sd->balance_interval))
> > +			next_balance = sd->last_balance
> > +					+ sd->balance_interval;
> 
> don't we have to do, msecs_to_jiffies(sd->balance_interval)?

Well that is certainly a bug here. Is this better?

Scheduler: Fix next_interval determination in idle_balance().

The intervals of domains that do not have SD_BALANCE_NEWIDLE must
be considered for the calculation of the time of the next balance.
Otherwise we may defer rebalancing forever.

Siddha also spotted that the conversion of the balance interval
to jiffies is missing. Fix that to.

Signed-off-by: Christop Lameter <clameter@sgi.com>

Index: linux-2.6.22-rc4-mm2/kernel/sched.c
===================================================================
--- linux-2.6.22-rc4-mm2.orig/kernel/sched.c	2007-06-18 20:41:46.000000000 -0700
+++ linux-2.6.22-rc4-mm2/kernel/sched.c	2007-06-18 20:44:00.000000000 -0700
@@ -2493,17 +2493,18 @@ static void idle_balance(int this_cpu, s
 	unsigned long next_balance = jiffies + 60 *  HZ;
 
 	for_each_domain(this_cpu, sd) {
-		if (sd->flags & SD_BALANCE_NEWIDLE) {
+		unsigned long interval;
+
+		if (sd->flags & SD_BALANCE_NEWIDLE)
 			/* If we've pulled tasks over stop searching: */
-			pulled_task = load_balance_newidle(this_cpu,
-							this_rq, sd);
-			if (time_after(next_balance,
-				  sd->last_balance + sd->balance_interval))
-				next_balance = sd->last_balance
-						+ sd->balance_interval;
-			if (pulled_task)
-				break;
-		}
+			pulled_task = load_balance_newidle(this_cpu,this_rq, sd);
+
+		interval = msecs_to_jiffies(sd->balance_interval);
+		if (time_after(next_balance,
+			  sd->last_balance + interval))
+			next_balance = sd->last_balance + interval;
+		if (pulled_task)
+			break;
 	}
 	if (!pulled_task)
 		/*

-
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