From: Sepherosa Ziehau <sephe@dragonflybsd.org>
Date: Fri, 25 Nov 2011 06:17:43 +0000 (+0800)
Subject: x86_64/ioapic_abi: Disable interrupt load balance by default
X-Git-Tag: v3.0.0~571
X-Git-Url: https://gitweb.dragonflybsd.org/~tuxillo/dragonfly.git/commitdiff_plain/2b195d6a566cb8441f5d6d66363235683bbd92af

x86_64/ioapic_abi: Disable interrupt load balance by default

Add hw.ioapic.gsi.balance tunable to enable/disable interrupt
load balance.  It is disabled by default.
---

diff --git a/sys/platform/pc64/apic/ioapic_abi.c b/sys/platform/pc64/apic/ioapic_abi.c
index a744118750..49084383e2 100644
--- a/sys/platform/pc64/apic/ioapic_abi.c
+++ b/sys/platform/pc64/apic/ioapic_abi.c
@@ -511,6 +511,7 @@ struct machintr_abi MachIntrABI_IOAPIC = {
 
 static int	ioapic_abi_extint_irq = -1;
 static int	ioapic_abi_line_irq_max;
+static int	ioapic_abi_gsi_balance;
 
 struct ioapic_irqinfo	ioapic_irqs[IOAPIC_HWI_VECTORS];
 
@@ -670,6 +671,8 @@ ioapic_abi_initmap(void)
 {
 	int cpu;
 
+	kgetenv_int("hw.ioapic.gsi.balance", &ioapic_abi_gsi_balance);
+
 	/*
 	 * NOTE: ncpus is not ready yet
 	 */
@@ -981,6 +984,9 @@ ioapic_abi_gsi_cpuid(int irq, int gsi)
 
 	KKASSERT(gsi >= 0);
 
+	if (!ioapic_abi_gsi_balance)
+		return 0;
+
 	if (irq == 0 || gsi == 0) {
 		if (bootverbose) {
 			kprintf("IOAPIC: irq %d, gsi %d -> cpu0 (0)\n",