Libguestfs - Sep 2019 - [PATCH] v2v: Use cacheextents if possible for vddk input

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@redhat.com>
---
 v2v/input_libvirt_vddk.ml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/v2v/input_libvirt_vddk.ml b/v2v/input_libvirt_vddk.ml
index a8e4fd5ac78e..cc63f77ce825 100644
--- a/v2v/input_libvirt_vddk.ml
+++ b/v2v/input_libvirt_vddk.ml
@@ -284,6 +284,9 @@ object (self)
         add_arg "--selinux-label"; add_arg
"system_u:object_r:svirt_socket_t:s0"
       );
 
+      if shell_command "nbdkit --filter cacheextents memory 1M --run true
2>/dev/null" = 0
+      then add_arg "--filter=cacheextents";
+
       (* Name of the plugin.  Everything following is a plugin parameter. *)
       add_arg "vddk";
 
-- 
2.23.0

On Fri, Sep 20, 2019 at 10:56:51AM +0200, 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@redhat.com>
> ---
>  v2v/input_libvirt_vddk.ml | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/v2v/input_libvirt_vddk.ml b/v2v/input_libvirt_vddk.ml
> index a8e4fd5ac78e..cc63f77ce825 100644
> --- a/v2v/input_libvirt_vddk.ml
> +++ b/v2v/input_libvirt_vddk.ml
> @@ -284,6 +284,9 @@ object (self)
>          add_arg "--selinux-label"; add_arg
"system_u:object_r:svirt_socket_t:s0"
>        );
>  
> +      if shell_command "nbdkit --filter cacheextents memory 1M --run
true 2>/dev/null" = 0
> +      then add_arg "--filter=cacheextents";
> +
>        (* Name of the plugin.  Everything following is a plugin parameter.
*)
>        add_arg "vddk";
This brings up back to the long-delayed nbdkit series:

  https://www.redhat.com/archives/libguestfs/2019-July/msg00200.html

In this series I've got a generic Nbdkit module which has a common
function for creating nbdkit instances.  It uses this to detect if a
filter is available:

  if Sys.file_exists (filterdir // "nbdkit-readahead-filter.so") then
(
    add_arg "--filter"; add_arg "readahead"
  );

While this is incidental to the current patch, I would really
appreciate someone to review the above series.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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