Libguestfs - Nov 2019 - [PATCH v2v v2] nbdkit: 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>
---
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.
    *)
-- 
2.24.0

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@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.

-- 
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