[PATCH] x86_64: resize NR_IRQS for large machines (re-submit)
From: Alan Mayer
Date: Wed Mar 26 2008 - 17:11:42 EST
Subject: [PATCH] x86_64: resize NR_IRQS for large machines
From: Alan Mayer <ajm@xxxxxxx>
On machines with very large numbers of cpus, tables that are dimensioned
by NR_IRQS get very large, especially the irq_desc table. They are also
very sparsely used. When the cpu count is > MAX_IO_APICS, use MAX_IO_APICS
to set NR_IRQS, otherwise use NR_CPUS.
Signed-off-by: Alan Mayer <ajm@xxxxxxx>
Reviewed-by: Christoph Lameter <clameter@xxxxxxx>
---
===================================================================
--- v2.6.25-rc6.orig/include/asm-x86/irq_64.h 2008-03-19 16:52:52.000000000 -0500
+++ v2.6.25-rc6/include/asm-x86/irq_64.h 2008-03-26 14:02:32.000000000 -0500
@@ -10,6 +10,8 @@
* <tomsoft@xxxxxxxxxxxxxxxxxxxxxxxxx>
*/
+#include <asm/apicdef.h>
+
#define TIMER_IRQ 0
/*
@@ -31,7 +33,11 @@
#define FIRST_SYSTEM_VECTOR 0xef /* duplicated in hw_irq.h */
-#define NR_IRQS (NR_VECTORS + (32 *NR_CPUS))
+#if NR_CPUS < MAX_IO_APICS
+#define NR_IRQS (NR_VECTORS + (32 * NR_CPUS))
+#else
+#define NR_IRQS (NR_VECTORS + (32 * MAX_IO_APICS))
+#endif
#define NR_IRQ_VECTORS NR_IRQS
static __inline__ int irq_canonicalize(int irq)
Index: v2.6.25-rc6/include/linux/kernel_stat.h
===================================================================
--- v2.6.25-rc6.orig/include/linux/kernel_stat.h 2008-03-19 16:53:00.000000000 -0500
+++ v2.6.25-rc6/include/linux/kernel_stat.h 2008-03-20 11:12:27.000000000 -0500
@@ -1,11 +1,11 @@
#ifndef _LINUX_KERNEL_STAT_H
#define _LINUX_KERNEL_STAT_H
-#include <asm/irq.h>
#include <linux/smp.h>
#include <linux/threads.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
+#include <asm/irq.h>
#include <asm/cputime.h>
/*
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/