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sparc64: On non-Niagara, need to touch NMI watchdog in NOHZ mode.

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When we're idling in NOHZ mode, timer interrupts are not running.

Evidence of processing timer interrupts is what the NMI watchdog
uses to determine if the CPU is stuck.

On Niagara, we'll yield the cpu.  This will make the cpu, at
worst, hang out in the hypervisor until an interrupt arrives.
This will prevent the NMI watchdog timer from firing.

However on non-Niagara we just loop executing instructions
which will cause the NMI watchdog to keep firing.  It won't
see timer interrupts happening so it will think the cpu is
stuck.

Fix this by touching the NMI watchdog in the cpu idle loop
on non-Niagara machines.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2009-02-02 21:57:48 -08:00
parent e5553a6d04
commit 802c64b310
1 changed files with 4 additions and 1 deletions
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5
arch/sparc/kernel/process_64.c
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@ -29,6 +29,7 @@
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/sysrq.h>
#include <linux/nmi.h>
#include <asm/uaccess.h>
#include <asm/system.h>
@ -52,8 +53,10 @@
static void sparc64_yield(int cpu)
{
if (tlb_type != hypervisor)
if (tlb_type != hypervisor) {
touch_nmi_watchdog();
return;
}
clear_thread_flag(TIF_POLLING_NRFLAG);
smp_mb__after_clear_bit();