Re: [PATCH v3 2/3] Introduce migration precopy policy

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 25/09/17 19:55, Jennifer Herbert wrote:
> @@ -46,7 +60,22 @@ struct save_callbacks {
>       */
>      int (*suspend)(void* data);
>  
> -    /* Called after the guest's dirty pages have been
> +    /*
> +     * Called before and after every batch of page data sent during
> +     * the precopy phase of a live migration to ask the caller what
> +     * to do next based on the current state of the precopy migration.

How is the callback supposed to determine whether it is before or ahead
of the data batch?

As far as I can tell, its not possible.

~Andrew

> +     *
> +     * Should return one of the values listed below:
> +     */
> +#define XGS_POLICY_ABORT          (-1) /* Abandon the migration entirely
> +                                        * and tidy up. */
> +#define XGS_POLICY_CONTINUE_PRECOPY 0  /* Remain in the precopy phase. */
> +#define XGS_POLICY_STOP_AND_COPY    1  /* Immediately suspend and transmit the
> +                                        * remaining dirty pages. */
> +    precopy_policy_t precopy_policy;
> +
> +    /*
> +     * Called after the guest's dirty pages have been
>       *  copied into an output buffer.
>       * Callback function resumes the guest & the device model,
>       *  returns to xc_domain_save.
>


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