svn commit: r278471 - head/sys/powerpc/pseries

[Nathan Whitehorn]

Author: nwhitehorn
Date: Mon Feb  9 19:21:54 2015
New Revision: 278471
URL: https://svnweb.freebsd.org/changeset/base/278471

Log:
  Distribute interrupts across multiple CPUs in SMP configurations instead of sending them
  all to CPU 0.

Modified:
  head/sys/powerpc/pseries/xics.c

Modified: head/sys/powerpc/pseries/xics.c
==============================================================================
--- head/sys/powerpc/pseries/xics.c	Mon Feb  9 19:20:59 2015	(r278470)
+++ head/sys/powerpc/pseries/xics.c	Mon Feb  9 19:21:54 2015	(r278471)
@@ -197,13 +197,25 @@ xicp_bind(device_t dev, u_int irq, cpuse
 {
 	struct xicp_softc *sc = device_get_softc(dev);
 	cell_t status, cpu;
+	int ncpus, i;
 
 	/*
-	 * This doesn't appear to actually support affinity groups, so just
-	 * use the first CPU.
+	 * This doesn't appear to actually support affinity groups, so pick a
+	 * random CPU.
 	 */
 	CPU_FOREACH(cpu)
-		if (CPU_ISSET(cpu, &cpumask)) break;
+		if (CPU_ISSET(cpu, &cpumask)) ncpus++;
+
+	i = mftb() % ncpus;
+	ncpus = 0;
+	CPU_FOREACH(cpu) {
+		if (!CPU_ISSET(cpu, &cpumask))
+			continue;
+		if (ncpus == i)
+			break;
+		ncpus++;
+	}
+	
 
 	rtas_call_method(sc->ibm_set_xive, 3, 1, irq, cpu, XICP_PRIORITY,
 	    &status);