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[Xen-users] RE: [Xen-devel] NR_IRQ limit

To: Eric Windisch <eric@xxxxxxxxxxxx>, "xen-users@xxxxxxxxxxxxxxxxxxx" <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-users] RE: [Xen-devel] NR_IRQ limit
From: "Subrahmanian, Raj" <raj.subrahmanian@xxxxxxxxxx>
Date: Fri, 29 Feb 2008 16:13:31 -0600
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Thread-topic: [Xen-devel] NR_IRQ limit
Eric,
I think you are trying to boot large numbers of VMs.
In that case, you will need to change the NR_DYNIRQS value in 
./linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/irq_vectors.h and recompile 
your Dom0.
You might also find it useful to increase Xen's heap (using the boot time 
option xenheap_megabytes).
Raj

>-----Original Message-----
>From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
>Eric Windisch
>Sent: Thursday, February 28, 2008 1:37 PM
>To: xen-users@xxxxxxxxxxxxxxxxxxx
>Subject: [Xen-devel] NR_IRQ limit
>
>(Originally posted to -users but I received no response there.   I
>figure this question might be better suited to those on -devel
>anyway...)
>
>I've finally hit the NR_IRQ limit in Xen 3.2-1.  I'd like to
>increase this, which I suspect is as simple as increasing
>NR_VECTORS in include/
>asm-x86/mach-default/irq_vectors.h.   Has anyone else had to do this,
>is this all that I'll need to do, or will I run into other issues?   I
>will need to increase the limit from its default of 256 to 1536.
>
>My other question is, will I need to modify or otherwise
>recompile my Linux kernel (2.8.18-xen.hg, rev=416)?
>
>As a suggestion, I'd really like to see this limit
>user-configurable at compile time, without having to edit the
>source...  my server is only at approximately 25% of its
>expected capacity, so I'd imagine that even those with smaller
>machines could be hitting this limit.
>Particularly since I built such a bulky (and expensive)
>server, I'd really like to have Xen scale...
>
>Thank you,
>
>Eric Windisch
>GrokThis.net
>
>PH: 1-800-630-0476
>IM: support@xxxxxxxxxxxx (jabber/xmpp)
>IM: grokthissupport (AIM)
>IM: grokthisnet (Yahoo)
>
>
>
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