[PATCH 0/1] libxl: set stub domain size based on VRAM size

[PATCH 0/1] libxl: set stub domain size based on VRAM size

[Eric Shelton]

I ran into crashes with qemu-traditional stub domain when 16 MB was
assigned to the stdvga virtual video adapter.  These were occurring due
to an out of memory condition arising from stub domains having a fixed
size of 32 MB, with half of that being demanded for video.  Assuming the
the original value of 32 MB was based on having a 4 MB video adapter,
this increases the stub domain size by however much the VRAM exceeds 4 MB. 

Eric Shelton (1):
  libxl: set stub domain size based on VRAM size

 tools/libxl/libxl_dm.c | 2 ++
 1 file changed, 2 insertions(+)

-- 
2.1.0

[PATCH 1/1] libxl: set stub domain size based on VRAM size

[Eric Shelton]

Allocate additional memory to the stub domain for qemu-traditional if
more than 4 MB is assigned to the video adapter to avoid out of memory
condition for QEMU.

Signed-off-by: Eric Shelton <eshelton@pobox.com>
---
 tools/libxl/libxl_dm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 317a8eb..9a5a937 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -1087,6 +1087,8 @@ void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state *sdss)
 
     dm_config->b_info.max_vcpus = 1;
     dm_config->b_info.max_memkb = 32 * 1024;
+    if (guest_config->b_info.video_memkb > 4096)
+        dm_config->b_info.max_memkb += guest_config->b_info.video_memkb - 4096;
     dm_config->b_info.target_memkb = dm_config->b_info.max_memkb;
 
     dm_config->b_info.u.pv.features = "";
-- 
2.1.0

Re: [PATCH 1/1] libxl: set stub domain size based on VRAM size

[Ian Jackson]

Eric Shelton writes ("[PATCH 1/1] libxl: set stub domain size based on VRAM size"):
> Allocate additional memory to the stub domain for qemu-traditional if
> more than 4 MB is assigned to the video adapter to avoid out of memory
> condition for QEMU.

>      dm_config->b_info.max_vcpus = 1;
>      dm_config->b_info.max_memkb = 32 * 1024;
> +    if (guest_config->b_info.video_memkb > 4096)
> +        dm_config->b_info.max_memkb += guest_config->b_info.video_memkb - 4096;

Thanks for diagnosing this.  This seems a reasonable approach to me.
I have only one small stylistic comment: please use max() as found in
libxl_internal.h.

Eg,

      dm_config->b_info.max_memkb = 28 * 1024 +
           max(guest_config->b_info.video_memkb, 4096);

Ian.

Re: [PATCH 1/1] libxl: set stub domain size based on VRAM size

[Samuel Thibault]

Eric Shelton, le Fri 10 Jul 2015 11:36:02 -0400, a écrit :
> Allocate additional memory to the stub domain for qemu-traditional if
> more than 4 MB is assigned to the video adapter to avoid out of memory
> condition for QEMU.
> 
> Signed-off-by: Eric Shelton <eshelton@pobox.com>

Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

> ---
>  tools/libxl/libxl_dm.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index 317a8eb..9a5a937 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -1087,6 +1087,8 @@ void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state *sdss)
>  
>      dm_config->b_info.max_vcpus = 1;
>      dm_config->b_info.max_memkb = 32 * 1024;
> +    if (guest_config->b_info.video_memkb > 4096)
> +        dm_config->b_info.max_memkb += guest_config->b_info.video_memkb - 4096;
>      dm_config->b_info.target_memkb = dm_config->b_info.max_memkb;
>  
>      dm_config->b_info.u.pv.features = "";
> -- 
> 2.1.0
> 

-- 
Samuel
Client: "This program has been successfully installed."
Vendeur (surpris): "Et où voyez-vous une erreur ?"
Client: "C'est << HAS BEEN >> !"

Re: [PATCH 0/1] libxl: set stub domain size based on VRAM size

[Samuel Thibault]

Eric Shelton, le Fri 10 Jul 2015 11:36:01 -0400, a écrit :
> Assuming the the original value of 32 MB was based on having a 4 MB
> video adapter,

In my memory that was the case, yes.

Samuel