Re: [Xen-devel] [PATCH 4 of 6] libxl: support suspend_cancel in domain_resume

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-01-31 at 17:52 +0000, Shriram Rajagopalan wrote:
> On Tue, Jan 31, 2012 at 2:00 AM, Ian Campbell
> <Ian.Campbell@xxxxxxxxxx> wrote:
>         On Tue, 2012-01-31 at 01:05 +0000, rshriram@xxxxxxxxx
>         wrote:Please can you add a few words about what fast means and
>         when its use
>         
>         would be appropriate.
>         
>         I'm not sure fast is right word -- it happens that this
>         mechanism is
>         faster but isn't the real meaning "co-operative" or something
>         along
>         those lines?
>         
>         Would a better name be libxl_domain_suspend_cancel, sharing a
>         common
>         helper internally with libxl_domain_resume?
>         
> 
> The explanation is already there, on top of xc_domain_resume in libxc.

It says that fast == cooperative resume but my concern was whether
"fast" is the right word for this parameter. Fast isn't really the
salient property here -- the fact that it requires guest cooperation
(which does happen to make it faster) is.

Anyway, regardless of what it is called it should be explained as part
of the libxl function otherwise users of libxl are never going to see
it.

[...]
> As for guests supporting this fast suspend, almost all guests (pv/hvm
> linux/windows) do support suspend_cancel. IIRC, I think some very old
> kernels didnt have this ability.

Old kernel or not, how do we detect it?

Ian.




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