Re: [PATCH 2 of 8] libxl: introduce libxl_set_relative_memory_target

[Ian Jackson <Ian.Jackson@eu.citrix.com>]

Stefano Stabellini writes ("[Xen-devel] [PATCH 2 of 8] libxl: introduce libxl_set_relative_memory_target"):
> libxl: introduce libxl_set_relative_memory_target
> 
> Introduce libxl_set_relative_memory_target to modify the memory target
> of a domain by a relative amount of memory in a single xenstore
> transaction.
> Modify libxl_set_memory_target to use xenstore transactions.
> The first time we are reading/writing dom0 memory target, fill the
> informations in xenstore if they are missing.

>  int libxl_set_memory_target(libxl_ctx *ctx, uint32_t domid,
>                              uint32_t target_memkb, int enforce)

See my earlier comments about memory targets.  I don't think it makes
much sense to give a domain a memory target and then let it exceed it.
So I think "enforce" should be abolished (as if it were always set).

Also please can you try to keep your code to <75ish columns ? :-)
(75 because there should be room for > and + quoting without wrap
damage.)

>  int libxl_set_memory_target(libxl_ctx *ctx, uint32_t domid,
>                 uint32_t target_memkb, int enforce)
...
> +int libxl_set_relative_memory_target(libxl_ctx *ctx, uint32_t
> +            domid, int32_t relative_target_memkb, int enforce)

These functions are really rather too similar for my taste.  They
seem to differ only in whether they read the existing target and add
it on.  Surely they should be combined.

Also, I don't really think this patch to introuce the relative setting
function should involves adding a lot of code to the absolute setting
function.  It's a shame that we have to set so many different copies
of the same value, but if we do then that should be done in a separate
patch first perhaps ?

Ian.