Re: [PATCH] Remove vcpu_avail from the S-Expression that's passed on the wire

[Anthony Liguori <aliguori@us.ibm.com>]

While looking into this bug, I realized that the vcpu_avail stuff in 
Xend is broken in general.  If the guest uses sysfs for hotplugging, the 
vcpu_avail bitmap will be inconsistent.  I've opened a bug in bugzilla 
about it that explains in more detail with my plan on how to clean this 
up for 3.0.3.

If the user uses sysfs to hotplug VCPUs, later calls to xm vcpu-set will 
result in the wrong thing happening.  I don't think this is a 
show-stopper for 3.0.2 but we should at least document it.

http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=590

Regards,

Anthony Liguori

Anthony Liguori wrote:
> Third time's a charm right :-)
>
> vcpu_avail is the configuration parameter that's tripping us up on 
> large SMP systems.  Instead of modifying the XML-RPC layer, a much 
> less invasive solution is just to remove vcpu_avail from the 
> S-Expression that's passed over the wire.  The vcpu_avail parameter is 
> not used by xm so this seems like a pretty reasonable thing to do.  It 
> certainly feels less hacky.
>
> Regards,
>
> Anthony Liguori
> ------------------------------------------------------------------------
>
> # HG changeset patch
> # User anthony@rhesis.austin.ibm.com
> # Node ID 96c1e3c2d336a0f9cdb9e074c737e7026cede171
> # Parent  4109c4e7804abeabe3b222673f2ba4dd1375be53
> Remove vcpu_avail from the public S-Expression that's passed over the wire.
> This trips up the XML-RPC layer on large SMP systems and isn't actually used
> by xm.
>
> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
>
> diff -r 4109c4e7804a -r 96c1e3c2d336 tools/python/xen/xend/server/XMLRPCServer.py
> --- a/tools/python/xen/xend/server/XMLRPCServer.py	Tue Mar 28 13:19:22 2006
> +++ b/tools/python/xen/xend/server/XMLRPCServer.py	Tue Mar 28 19:29:40 2006
> @@ -24,6 +24,7 @@
>  
>  from xen.xend.XendClient import XML_RPC_SOCKET, ERROR_INVALID_DOMAIN
>  from xen.xend.XendError import *
> +from types import ListType
>  
>  def lookup(domid):
>      info = XendDomain.instance().domain_lookup_by_name_or_id(domid)
> @@ -35,24 +36,36 @@
>      info = lookup(domid)
>      return getattr(info, fn)(*args)
>  
> +# vcpu_avail is a long and is not needed by the clients.  It's far easier
> +# to just remove it then to try and marshal the long.
> +def fixup_sxpr(sexpr):
> +    ret = []
> +    for k in sexpr:
> +        if type(k) is ListType:
> +            if len(k) != 2 or k[0] != 'vcpu_avail':
> +                ret.append(fixup_sxpr(k))
> +        else:
> +            ret.append(k)
> +    return ret
> +
>  def domain(domid):
>      info = lookup(domid)
> -    return info.sxpr()
> +    return fixup_sxpr(info.sxpr())
>  
>  def domains(detail=1):
>      if detail < 1:
>          return XendDomain.instance().list_names()
>      else:
>          domains = XendDomain.instance().list_sorted()
> -        return map(lambda dom: dom.sxpr(), domains)
> +        return map(lambda dom: fixup_sxpr(dom.sxpr()), domains)
>  
>  def domain_create(config):
>      info = XendDomain.instance().domain_create(config)
> -    return info.sxpr()
> +    return fixup_sxpr(info.sxpr())
>  
>  def domain_restore(src):
>      info = XendDomain.instance().domain_restore(src)
> -    return info.sxpr()    
> +    return fixup_sxpr(info.sxpr())
>  
>  def get_log():
>      f = open(XendLogging.getLogFilename(), 'r')
>   
> ------------------------------------------------------------------------
>
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