On 02/18/2014 01:50 AM, mrhi...@linux.vnet.ibm.com wrote: > From: "Michael R. Hines" <mrhi...@us.ibm.com> > > New capabilities include the use of RDMA acceleration, > use of network buffering, and keepalive support, as documented > in patch #1. > > Signed-off-by: Michael R. Hines <mrhi...@us.ibm.com> > --- > qapi-schema.json | 36 +++++++++++++++++++++++++++++++++++- > 1 file changed, 35 insertions(+), 1 deletion(-) >
> +# Only for performance testing. (Since 2.x)
> +#
> +# @mc-rdma-copy: MC requires creating a local-memory checkpoint before
> +# transmission to the destination. This requires heavy use of
> +# memcpy() which dominates the processor pipeline. This option
> +# makes use of *local* RDMA to perform the copy instead of the CPU.
> +# Enabled by default only if the migration transport is RDMA.
> +# Disabled by default otherwise. (Since 2.x)
How does that work? If I query migration capabilities before requesting
a migration, what state am I going to read? Is there coupling where I
would observe the state of this flag change merely because I did some
other action? And if so, then how do I know that explicitly setting
this flag won't be undone by similar coupling?
It sounds like you are describing a tri-state option (unspecified so
default to migration transport, explicitly disabled, explicitly
enabled); but that doesn't work for something that only lists boolean
capabilities. The only way around that is to have 2 separate
capabilities (one on whether to base decision on transport or to honor
override, and the other to provide the override value which is ignored
when defaulting by transport).
> +#
> +# @rdma-keepalive: RDMA connections do not timeout by themselves if a peer
> +# has disconnected prematurely or failed. User-level keepalives
> +# allow the migration to abort cleanly if there is a problem with the
> +# destination host. For debugging, this can be problematic as
> +# the keepalive may cause the peer to abort prematurely if we are
> +# at a GDB breakpoint, for example.
> +# Enabled by default. (Since 2.x)
Enabled-by-default is an interesting choice, but I suppose it is okay.
> +#
> # Since: 1.2
> ##
> { 'enum': 'MigrationCapability',
> - 'data': ['xbzrle', 'x-rdma-pin-all', 'auto-converge', 'zero-blocks'] }
> + 'data': ['xbzrle',
> + 'rdma-pin-all',
> + 'auto-converge',
> + 'zero-blocks',
> + 'mc',
> + 'mc-net-disable',
> + 'mc-rdma-copy',
> + 'rdma-keepalive'
> + ] }
>
> ##
> # @MigrationCapabilityStatus
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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