On Fri, 2010-02-19 at 17:05 +1100, Michael Neuling wrote:

quoted

 include/linux/sched.h |    2 +-
 kernel/sched_fair.c   |   61 +++++++++++++++++++++++++++++++++++++++++++++--

-

quoted

 2 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0eef87b..42fa5c6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h

@@ -849,7 +849,7 @@ enum cpu_idle_type {
 #define SD_POWERSAVINGS_BALANCE	0x0100	/* Balance for power savings */
 #define SD_SHARE_PKG_RESOURCES	0x0200	/* Domain members share cpu pkg

 resources */

quoted

 #define SD_SERIALIZE		0x0400	/* Only a single load balancing instanc

e */

quoted

-
+#define SD_ASYM_PACKING		0x0800

Would we eventually add this to SD_SIBLING_INIT in a arch specific hook,
or is this ok to add it generically?

I'd think we'd want to keep that limited to architectures that actually
need it.

quoted

+static int update_sd_pick_busiest(struct sched_domain *sd,
+	       			  struct sd_lb_stats *sds,
+				  struct sched_group *sg,
+			  	  struct sg_lb_stats *sgs)
+{
+	if (sgs->sum_nr_running > sgs->group_capacity)
+		return 1;
+
+	if (sgs->group_imb)
+		return 1;
+
+	if ((sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running) {
+		if (!sds->busiest)
+			return 1;
+
+		if (group_first_cpu(sds->busiest) < group_first_cpu(group))

"group" => "sg" here? (I get a compile error otherwise)

Oh, quite ;-)

quoted

+static int check_asym_packing(struct sched_domain *sd,
+				    struct sd_lb_stats *sds, 
+				    int cpu, unsigned long *imbalance)
+{
+	int i, cpu, busiest_cpu;

Redefining cpu here.  Looks like the cpu parameter is not really needed?

Seems that way indeed, I went back and forth a few times on the actual
implementation of this function (which started out live as a copy of
check_power_save_busiest_group), its amazing there were only these two
compile glitches ;-)

quoted

+
+	if (!(sd->flags & SD_ASYM_PACKING))
+		return 0;
+
+	if (!sds->busiest)
+		return 0;
+
+	i = 0;
+	busiest_cpu = group_first_cpu(sds->busiest);
+	for_each_cpu(cpu, sched_domain_span(sd)) {
+		i++;
+		if (cpu == busiest_cpu)
+			break;
+	}
+
+	if (sds->total_nr_running > i)
+		return 0;
+
+	*imbalance = sds->max_load;
+	return 1;
+}