[Libguestfs] [PATCH v2v v2] nbdkit: Use cacheextents if possible for vddk input

[Richard W.M. Jones]

On Thu, Nov 14, 2019 at 01:56:33PM +0100, Martin Kletzander wrote:
> It does not need configuring and speeds up the process of requesting extents if
> the client asks for them one by one (like qemu-img).
> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
> Essentially a v2 of the following patch since now there is a probing function:
> 
>   https://www.redhat.com/archives/libguestfs/2019-September/msg00249.html
> 
>  v2v/nbdkit.ml | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/v2v/nbdkit.ml b/v2v/nbdkit.ml
> index 89fca337cbaa..77d2a506dc41 100644
> --- a/v2v/nbdkit.ml
> +++ b/v2v/nbdkit.ml
> @@ -169,6 +169,13 @@ let common_create ?bandwidth plugin_name plugin_args plugin_env =
>      )
>      else [] in
>  
> +  (* Caching extents speeds up qemu-img, especially its consecutive
> +     block_status requests with req_one=1.
> +  *)
> +  if probe_filter "cacheextents" then (
> +    add_arg "--filter"; add_arg "cacheextents"
> +  );
> +
>    (* Retry filter (if it exists) can be used to get around brief
>     * interruptions in service.  It must be closest to the plugin.
>     *)

ACK

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
Fedora Windows cross-compiler. Compile Windows programs, test, and
build Windows installers. Over 100 libraries supported.
http://fedoraproject.org/wiki/MinGW