Re: XEN 4.0 + 2.6.31.13 pvops kernel : system crashes on starting 155th domU

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Apr 28, 2010 at 03:51:19PM -0700, Yuvraj Agarwal wrote:
> I tried making the change in 
> linux-2.6-pvops.git/arch/x86/include/asm/irq_vectors.h
> 
> It was:
> #define NR_VECTORS                     256
> I changed it to
> #define NR_VECTORS                       1024
> 
> I still get the same number of nr_irqs  (dmesg | grep -i nr_irq) before and 
> after the change.
> 
> [    0.000000] nr_irqs_gsi: 48
> [    0.500076] NR_IRQS:5120 nr_irqs:944

That looks to be different from the previous bootup:
[    0.000000] NR_IRQS:4352 nr_irqs:256

?
> 
> Also, as earlier it crashes on the same number of domU (154). I didn’t 
> mention earlier, this a dual core Nehalem machine  -- 2 (sockets) * 4 cores 
> per CPU * 2 (hyperthreading)

Lots of logical CPUs, weird that your nr_irqs initially was that much
lower.

Anyhow, you mentioned that you narrowed it down to not being enough IRQs
- how did you find that out? Was there an kernel message when you
  started the 155th guest?
 

Oh, also you say that the /proc/interrupts showed the number descending
from 255 down to 89. With this it should have started at 944 and gone
down to 49? Which roughly means 175 guests?