[Xen-devel] increasing the number of guests (NR_DYNIRQS)

[Luke S Crawford <lsc@xxxxxxxxx>]

So I'm setting up a server to host many very small domains, and I ran
into a problem where after I create about 60 guests, any addtional guests
start, but hang at 0 cpu usage-  they never do anything.  

grep Dynamic-irq /proc/interrupts | wc -l
256


I did some digging and found some old discussion of the topic[1]
and but the patches discussed there didn't work, I assume because the
linux/xen codebase has evolved since then.  I dug around and made this 
change:

xen-3.4-testing.hg/linux-2.6.18-xen.hg/include/asm-x86_64/mach-xen/irq_vectors.h

I changed:

#define NR_DYNIRQS           1024

(it defaults to 256)

two questions:  first, is this stupid?  domains appear to be working, and
I'm currently running north of 200 guests on the server.  

second, if this is indeed the right way to fix the problem, if I 
submitted a CONFIG_NR_DYNIRQS patch as Kier suggested in the referenced
post, would that be considered for acceptance upstream?



[1]http://lists.xensource.com/archives/html/xen-devel/2006-12/msg00353.html


-- 
Luke S. Crawford
http://prgmr.com/xen/         -   Hosting for the technically adept
http://nostarch.com/xen.htm   -   We don't assume you are stupid.  

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel