From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: XEN 4.0 + 2.6.31.13 pvops kernel : system crashes
	on starting 155th domU
Date: Thu, 29 Apr 2010 10:56:03 -0400
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To: Yuvraj Agarwal <yuvraj@cs.ucsd.edu>
Cc: xen-devel@lists.xensource.com, 'Keir Fraser' <keir.fraser@eu.citrix.com>, 'John McCullough' <jmccullo@cs.ucsd.edu>
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On Wed, Apr 28, 2010 at 03:51:19PM -0700, Yuvraj Agarwal wrote:
> I tried making the change in=20
> linux-2.6-pvops.git/arch/x86/include/asm/irq_vectors.h
>=20
> It was:
> #define NR_VECTORS                     256
> I changed it to
> #define NR_VECTORS                       1024
>=20
> I still get the same number of nr_irqs  (dmesg | grep -i nr_irq) before=
 and=20
> after the change.
>=20
> [    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

?
>=20
> Also, as earlier it crashes on the same number of domU (154). I didn=E2=
=80=99t=20
> mention earlier, this a dual core Nehalem machine  -- 2 (sockets) * 4 c=
ores=20
> 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?
=20

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?