Re: [Xen-devel] [PATCH 4 of 4] xenpaging: initial libxl support

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 2 Nov 2011, Olaf Hering wrote:
> diff -r a51d4fab351d -r ab5406a5b1d0 tools/libxl/libxl_create.c
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -429,6 +429,122 @@ retry_transaction:
>      return rc;
>  }
> 
> +static int create_xenpaging(libxl__gc *gc, char *dom_name, uint32_t domid,
> +                            libxl_domain_build_info *b_info)
> +{
> +    libxl__spawner_starting *buf_starting;
> +    libxl_string_list xpe = b_info->u.hvm.xenpaging_extra;
> +    int i, rc;
> +    char *logfile;
> +    int logfile_w, null;
> +    char *path, *dom_path, *value;
> +    char **args;
> +    char *xp;
> +    flexarray_t *xp_args;
> +    libxl_ctx *ctx = libxl__gc_owner(gc);
> +
> +    /* Nothing to do */
> +    if (!b_info->tot_memkb)
> +        return 0;

I think that using tot_memkb to store the actual memory target and then
checking whether is 0 to detect if paging is active/inactive is
confusing.
If tot_memkb is the pod target of the domain, we should be coherent and
set it equal to target_memkb when paging is inactive.


> @@ -34,6 +34,17 @@
>      libxl_domain_setmaxmem -> xen maximum
>      libxl_set_memory_target -> actual target
> 
> +    build maximum = RAM as seen inside the virtual machine
> +                    Guest OS has to configure itself for this amount of 
> memory
> +                    Increase/Decrease via memory hotplug of virtual hardware.
> +                   xl mem-max
> +    build start   = RAM usable by the guest OS
> +                    Guest OS sees balloon driver as memory hog
> +                    Increase/Decrease via commands to the balloon driver
> +                   xl mem-set
> +    actual target = RAM allocated for the guest
> +                    Increase/Decrease via commands to paging daemon
> +                   xl mem-paging_target (?)

maybe xl mem-paging is specific enough


>   === Domain memory breakdown: PV guests ==================================
> 
> diff -r a51d4fab351d -r ab5406a5b1d0 tools/libxl/libxl_types.idl
> --- a/tools/libxl/libxl_types.idl
> +++ b/tools/libxl/libxl_types.idl
> @@ -157,6 +157,7 @@ libxl_domain_build_info = Struct("domain
>      ("tsc_mode",        integer),
>      ("max_memkb",       uint32),
>      ("target_memkb",    uint32),
> +    ("tot_memkb",       uint32),
>      ("video_memkb",     uint32),
>      ("shadow_memkb",    uint32),
>      ("disable_migrate", bool),

I would like a comment somewhere of what tot_memkb is supposed to
represent.


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