irqbalance: add support for affinity_hint hook

This support is found in kernels 2.6.35 and beyond.  The new
affinity_hint hook found in /proc/irq/<num>/ can be populated
by underlying device drivers.  The cpumask in this file will
be used as a preferred affinity, allowing devices with
multiple interrupt sources (e.g. MSI-X enabled network devices)
to better control their NUMA locality of data flows.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>


git-svn-id: https://irqbalance.googlecode.com/svn/trunk@25 46b42954-3823-0410-bd82-eb80b452c9b5

irqbalance.c

@@ -80,7 +80,6 @@ int main(int argc, char** argv)
 	if (cache_domain_count==1)
 		one_shot_mode = 1;
 
-
 	if (!debug_mode)
 		if (daemon(0,0))
 			exit(EXIT_FAILURE);

irqlist.c

@@ -36,6 +36,26 @@ GList *interrupts;
 
 
 
+void get_affinity_hint(struct interrupt *irq, int number)
+{
+	char buf[PATH_MAX];
+	char *line = NULL;
+	size_t size = 0;
+	FILE *file;
+	sprintf(buf, "/proc/irq/%i/affinity_hint", number);
+	file = fopen(buf, "r");
+	if (!file)
+		return;
+	if (getline(&line, &size, file)==0) {
+		free(line);
+		fclose(file);
+		return;
+	}
+	cpumask_parse_user(line, strlen(line), irq->node_mask);
+	fclose(file);
+	free(line);
+}
+
 /*
  * This function classifies and reads various things from /proc about a specific irq 
  */
@@ -84,6 +104,8 @@ static void investigate(struct interrupt *irq, int number)
 			cpumask_parse_user(line, strlen(line), irq->allowed_mask);
 			fclose(file);
 			free(line);
+		} else if (strcmp(entry->d_name,"affinity_hint")==0) {
+			get_affinity_hint(irq, number);
 		} else {
 			irq->class = find_class(irq, entry->d_name);
 		}
@@ -134,6 +156,8 @@ void set_interrupt_count(int number, uint64_t count)
 
 		if (irq->number == number) {
 			irq->count = count;
+			/* see if affinity_hint changed */
+			get_affinity_hint(irq, number);
 			return;
 		}
 		item = g_list_next(item);

placement.c

@@ -257,6 +257,30 @@ static void place_packages(GList *list)
 }
 
 
+static void place_affinity_hint(GList *list)
+{
+	/* still need to balance best workload within the affinity_hint mask */
+	GList *iter;
+	struct interrupt *irq;
+
+	iter = g_list_first(list);
+	while (iter) {
+		irq = iter->data;
+		if (irq->balance_level == BALANCE_NONE) {
+			iter = g_list_next(iter);
+			continue;
+		}
+		if ((!cpus_empty(irq->node_mask)) &&
+		    (!cpus_equal(irq->mask, irq->node_mask)) &&
+		    (!cpus_full(irq->node_mask))) {
+			irq->old_mask = irq->mask;
+			irq->mask = irq->node_mask;
+		}
+
+		iter = g_list_next(iter);
+	}
+}
+
 
 static void do_unroutables(void)
 {
@@ -276,7 +300,8 @@ static void do_unroutables(void)
 		iter = g_list_first(packages);
 		while (iter) {
 			package = iter->data;
-			if (cpus_intersects(package->mask, irq->mask))
+			if (cpus_intersects(package->mask, irq->node_mask) ||
+			    cpus_intersects(package->mask, irq->mask))
 				package->workload += irq->workload;
 			iter = g_list_next(iter);
 		}
@@ -284,14 +309,16 @@ static void do_unroutables(void)
 		iter = g_list_first(cache_domains);
 		while (iter) {
 			cache_domain = iter->data;
-			if (cpus_intersects(cache_domain->mask, irq->mask))
+			if (cpus_intersects(cache_domain->mask, irq->node_mask)
+			    || cpus_intersects(cache_domain->mask, irq->mask))
 				cache_domain->workload += irq->workload;
 			iter = g_list_next(iter);
 		}
 		iter = g_list_first(cpus);
 		while (iter) {
 			cpu = iter->data;
-			if (cpus_intersects(cpu->mask, irq->mask))
+			if (cpus_intersects(cpu->mask, irq->node_mask) ||
+			    cpus_intersects(cpu->mask, irq->mask))
 				cpu->workload += irq->workload;
 			iter = g_list_next(iter);
 		}
@@ -323,4 +350,10 @@ void calculate_placement(void)
 		place_core(cache_domain);
 		iter = g_list_next(iter);
 	}
+	/*
+	 * if affinity_hint is populated on irq and is not set to
+	 * all CPUs (meaning it's initialized), honor that above
+	 * anything in the package locality/workload.
+	 */
+	place_affinity_hint(interrupts);
 }

types.h

@@ -81,6 +81,9 @@ struct interrupt {
 
 	cpumask_t	numa_mask;
 	cpumask_t	allowed_mask;
+
+	/* user/driver provided for smarter balancing */
+	cpumask_t	node_mask;
 };