[PATCH/RFC] Wrong account for cpus other than 0 on hotplug

[Glauber de Oliveira Costa <gcosta@redhat.com>]

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Hi,

Is a x86_64 system with multiple CPUs, process accounting is done wrong after
one cpu goes off and on again (i.e.: a CPU bounded process is running
but gets 0% cpu for a time, until situation becomes normal again). 

The following patch is a first attempt to fix it. The struct keeps
zeroed after HYPERVISOR_vcpu_op() is called, thus leading to wrong
results. Accounting seems to be done right without it. However, I'm not
100 % sure we can just poke it out. Comments on this are very welcome.


-- 
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"

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--- linux-2.6.18.x86_64/arch/i386/kernel/time-xen.c.orig	2006-10-13 13:06:12.000000000 -0400
+++ linux-2.6.18.x86_64/arch/i386/kernel/time-xen.c	2006-10-13 13:16:50.000000000 -0400
@@ -721,14 +721,8 @@ irqreturn_t timer_interrupt(int irq, voi
 
 static void init_missing_ticks_accounting(int cpu)
 {
-	struct vcpu_register_runstate_memory_area area;
 	struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu);
 
-	memset(runstate, 0, sizeof(*runstate));
-
-	area.addr.v = runstate;
-	HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu, &area);
-
 	per_cpu(processed_blocked_time, cpu) =
 		runstate->time[RUNSTATE_blocked];
 	per_cpu(processed_stolen_time, cpu) =

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