diff -rupN linux-2.6.12-rc1-mm4/arch/ppc64/Kconfig linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/arch/ppc64/Kconfig
--- linux-2.6.12-rc1-mm4/arch/ppc64/Kconfig	2005-03-31 21:08:24.000000000 +0200
+++ linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/arch/ppc64/Kconfig	2005-03-31 23:28:07.000000000 +0200
@@ -297,6 +297,7 @@ config SECCOMP
 
 endmenu
 
+source "drivers/perfctr/Kconfig"
 
 menu "General setup"
 
diff -rupN linux-2.6.12-rc1-mm4/arch/ppc64/kernel/misc.S linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/arch/ppc64/kernel/misc.S
--- linux-2.6.12-rc1-mm4/arch/ppc64/kernel/misc.S	2005-03-31 21:08:24.000000000 +0200
+++ linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/arch/ppc64/kernel/misc.S	2005-03-31 23:28:07.000000000 +0200
@@ -956,6 +956,12 @@ _GLOBAL(sys_call_table32)
 	.llong .sys32_request_key
 	.llong .compat_sys_keyctl
 	.llong .compat_sys_waitid
+	.llong .sys_ni_syscall		/* 273 reserved for sys_ioprio_set */
+	.llong .sys_ni_syscall		/* 274 reserved for sys_ioprio_get */
+	.llong .sys_vperfctr_open	/* 275 */
+	.llong .sys_vperfctr_control
+	.llong .sys_vperfctr_write
+	.llong .sys_vperfctr_read
 
 	.balign 8
 _GLOBAL(sys_call_table)
@@ -1232,3 +1238,9 @@ _GLOBAL(sys_call_table)
 	.llong .sys_request_key		/* 270 */
 	.llong .sys_keyctl
 	.llong .sys_waitid
+	.llong .sys_ni_syscall		/* 273 reserved for sys_ioprio_set */
+	.llong .sys_ni_syscall		/* 274 reserved for sys_ioprio_get */
+	.llong .sys_vperfctr_open	/* 275 */
+	.llong .sys_vperfctr_control
+	.llong .sys_vperfctr_write
+	.llong .sys_vperfctr_read
diff -rupN linux-2.6.12-rc1-mm4/arch/ppc64/kernel/process.c linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/arch/ppc64/kernel/process.c
--- linux-2.6.12-rc1-mm4/arch/ppc64/kernel/process.c	2005-03-31 21:07:46.000000000 +0200
+++ linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/arch/ppc64/kernel/process.c	2005-03-31 23:28:07.000000000 +0200
@@ -36,6 +36,7 @@
 #include <linux/kallsyms.h>
 #include <linux/interrupt.h>
 #include <linux/utsname.h>
+#include <linux/perfctr.h>
 
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
@@ -225,7 +226,9 @@ struct task_struct *__switch_to(struct t
 
 
 	local_irq_save(flags);
+	perfctr_suspend_thread(&prev->thread);
 	last = _switch(old_thread, new_thread);
+	perfctr_resume_thread(&current->thread);
 
 	local_irq_restore(flags);
 
@@ -323,6 +326,7 @@ void exit_thread(void)
 		last_task_used_altivec = NULL;
 #endif /* CONFIG_ALTIVEC */
 #endif /* CONFIG_SMP */
+	perfctr_exit_thread(&current->thread);
 }
 
 void flush_thread(void)
@@ -425,6 +429,8 @@ copy_thread(int nr, unsigned long clone_
  	 */
 	kregs->nip = *((unsigned long *)ret_from_fork);
 
+	perfctr_copy_task(p, regs);
+
 	return 0;
 }
 
diff -rupN linux-2.6.12-rc1-mm4/include/asm-ppc64/processor.h linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/include/asm-ppc64/processor.h
--- linux-2.6.12-rc1-mm4/include/asm-ppc64/processor.h	2005-03-31 21:08:31.000000000 +0200
+++ linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/include/asm-ppc64/processor.h	2005-03-31 23:28:07.000000000 +0200
@@ -574,6 +574,8 @@ struct thread_struct {
 	unsigned long	vrsave;
 	int		used_vr;	/* set if process has used altivec */
 #endif /* CONFIG_ALTIVEC */
+	/* performance counters */
+	struct vperfctr *perfctr;
 };
 
 #define ARCH_MIN_TASKALIGN 16
diff -rupN linux-2.6.12-rc1-mm4/include/asm-ppc64/unistd.h linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/include/asm-ppc64/unistd.h
--- linux-2.6.12-rc1-mm4/include/asm-ppc64/unistd.h	2005-03-31 21:07:54.000000000 +0200
+++ linux-2.6.12-rc1-mm4.perfctr27-ppc64-arch-hooks/include/asm-ppc64/unistd.h	2005-03-31 23:28:07.000000000 +0200
@@ -283,8 +283,14 @@
 #define __NR_request_key	270
 #define __NR_keyctl		271
 #define __NR_waitid		272
+/* 273 is reserved for ioprio_set */
+/* 274 is reserved for ioprio_get */
+#define __NR_vperfctr_open	275
+#define __NR_vperfctr_control	(__NR_vperfctr_open+1)
+#define __NR_vperfctr_write	(__NR_vperfctr_open+2)
+#define __NR_vperfctr_read	(__NR_vperfctr_open+3)
 
-#define __NR_syscalls		273
+#define __NR_syscalls		279
 #ifdef __KERNEL__
 #define NR_syscalls	__NR_syscalls
 #endif
