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

["Yuvraj Agarwal" <yuvraj@cs.ucsd.edu>]

Thank you for the pointer. Unfortunately, I was unable to find the message
you mentioned after looking through the archives...  

In my current kernel config (default 2.6.31.13 pvops kernel) I don't have
CONFIG_LEGACY_PTY_COUNT defined, perhaps because I have the following in
the .config ?

# CONFIG_LEGACY_PTYS is not set

Do you think setting the variable above and setting the
CONFIG_LEGACY_PTY_COUNT to a high value will help in this case?

--Yuvraj


-----Original Message-----
From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com] 
Sent: Tuesday, April 27, 2010 6:59 AM
To: Yuvraj Agarwal
Cc: xen-devel@lists.xensource.com
Subject: Re: [Xen-devel] XEN 4.0 + 2.6.31.13 pvops kernel : system crashes
on starting 155th domU

On Tue, Apr 27, 2010 at 12:41:07AM -0700, Yuvraj Agarwal wrote:
> Hi All, 
> 
>  
> 
> We are setting up a system with a large number of very small VMs for a
> project. We worked through a number of limitations, including those
> imposed by blktap2 devices and the number of dynamic IRQ (set kernel
> config NR_CPUS) etc. After these changes we were able to get to  154
domUs
> (!), but as soon as we start up the 155th domU the system crashes. We
> edited each domU config to have one blktap2 device (the disk image) and
> two virtual network interfaces each. 

This sounds strangly familiar. I believe somebody posted a question
about this a couple of months ago on the xen-devel mailing list and
found the answer. I think part of it was CONFIG_LEGACY_PTY_COUNT had to
be high. But I don't remember the exact details - you might want to
search the archive.