Re: [Xen-devel] [PATCH 1 of 2] libxl: Remus - suspend/postflush/commit callbacks

[Shriram Rajagopalan <rshriram@xxxxxxxxx>]

On Tue, Jan 31, 2012 at 2:53 AM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

> @@ -669,7 +715,27 @@ int libxl__domain_suspend_common(libxl__
>      }
>
>      memset(&callbacks, 0, sizeof(callbacks));
> -    callbacks.suspend = libxl__domain_suspend_common_callback;
> +    if (r_info != NULL) {
> +        /* save_callbacks:
> +         * suspend - called after expiration of checkpoint interval,
> +         *           to *suspend* the domain.
> +         *
> +         * postcopy - called after the domain's dirty pages have been
> +         *            copied into an output buffer. We *resume* the domain
> +         *            & the device model, return to the caller. Caller then
> +         *            flushes the output buffer, while the domain continues to run.
> +         *
> +         * checkpoint - called after the memory checkpoint has been flushed out
> +         *              into the network. Send the saved device state, *wait*
> +         *              for checkpoint ack and *release* the network buffer (TBD).
> +         *              Then *sleep* for the checkpoint interval.
> +         */

Please can you put this next to the definition of the struct (in
xenguest.h). Otherwise this patch looks ok to me.

Ian.

struct save_callbacks already has comments on these callbacks, it is generic though,
as the postcopy and checkpoint callbacks could be used even without Remus. One need
not necessarily do all the actions specified in the above comment.


But, with libxl/remus, it seemed proper to add more detailed comments to the code
that does other things in the callback, specific to remus/checkpointing.

shriram
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