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

[Jennifer Herbert <Jennifer.Herbert@citrix.com>]

On 26/09/17 12:02, Andrew Cooper wrote:
> 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

You look at the dirty_count.  It works well for me.
I can add that info to the comment.

-jenny

>> +     *
>> +     * 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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