Re: [PATCH] Inhibit NMI watchdog when Alt-SysRq-T operation is underway.

[darnok@68k.org]

On Mon, Jul 09, 2007 at 10:02:42AM -0400, Konrad Rzeszutek wrote:
> On large memory configuration with not so fast CPUs the NMI watchdog 
> is triggered when memory addresses are being gathered and printed. 
> The code paths for Alt-SysRq-t are sprinkled with touch_nmi_watchdog 
> in various places but not in this routine (or in the loop that utilizes
> this function). The patch has been tested for regression on large CPU+memory 
> configuration (128 logical CPUs + 224 GB) and 1,2,4,16-CPU sockets with various 
> memory sizes (1,2,4,6,20). 

And the patch:

diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index aac1c0b..b6e7d67 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -330,6 +330,10 @@ static int print_trace_stack(void *data,
 
 static void print_trace_address(void *data, unsigned long addr)
 {
+	static int i = 0;		
+	if (i && ((i % 8) == 0)) 
+		touch_nmi_watchdog();
+	i++;
 	printk_address(addr);
 }