Re: [Qemu-devel] [PATCH v5 10/12] rdma: introduce capability x-rdma-pin-all

[Eric Blake]

On 04/21/2013 03:17 PM, address@hidden wrote:
> From: "Michael R. Hines" <address@hidden>
> 
> This capability allows you to disable dynamic chunk registration
> for better throughput on high-performance links.
> 
> For example, using an 8GB RAM virtual machine with all 8GB of memory in
> active use and the VM itself is completely idle using a 40 gbps infiniband 
> link:
> 
> 1. x-pin-all disabled total time: approximately 7.5 seconds @ 9.5 Gbps
> 2. x-pin-all enabled total time: approximately 4 seconds @ 26 Gbps

Naming here doesn't match the actual bit name; but it is obvious enough
to know what you meant.

Thanks for doing this, by the way - the default-to-disabled is a bit
nicer to manage from libvirt's perspective.

> 
> These numbers would of course scale up to whatever size virtual machine
> you have to migrate using RDMA.
> 
> Enabling this feature does *not* have any measurable affect on
> migration *downtime*. This is because, without this feature, all of the
> memory will have already been registered already in advance during
> the bulk round and does not need to be re-registered during the successive
> iteration rounds.
> 
> Signed-off-by: Michael R. Hines <address@hidden>
> ---
>  include/migration/migration.h |    2 ++
>  migration.c                   |    9 +++++++++
>  qapi-schema.json              |    7 ++++++-
>  3 files changed, 17 insertions(+), 1 deletion(-)


> +++ b/qapi-schema.json
> @@ -602,10 +602,15 @@
>  #          This feature allows us to minimize migration traffic for certain 
> work
>  #          loads, by sending compressed difference of the pages
>  #
> +# @x-rdma-pin-all: (since 1.5) Controls whether or not the entire VM memory 
> footprint is 

Trailing whitespace, and line longer than 80 columns.  You ought to
rewrap this, and make sure it passes checkpatch.pl.

But since that is whitespace-only, feel free to add:

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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