Re: [Xen-devel] How to get the checkpoint size in remus code?

[Shriram Rajagopalan <rshriram@xxxxxxxxx>]

On Wed, Oct 3, 2012 at 4:11 AM, José Eduardo França <jefranca@xxxxxxxxx> wrote:
>
> I thought remus used xc_domain_save. Is this function used from live
> migration?
>
> Futhermore I have two doubts if really Remus takes the last iteration of
> live migration
>
> What's the function?

There is no specific function. xc_domain_save is where everything
happens. The infinite loop
that basically keeps sending checkpoints @ a particular frequency


> And how to get de I/O disk size on each period?
>

This depends on the disk backend. With blktap2 (unfortunately not
available in 3.* kernels)
tap-remus driver can give you the number of disk blocks sent per checkpoint.

With DRBD, it needs a little bit of hacking into the kernel module to
return the number of disk blocks
being sent with each checkpoint.


>> I'm doing my master research and I need to adapt remus code. Now... I
>> wanna get the checkpoint size (memory + disk) on each period. Does someone
>> know what function does this? I think some fd object's function in remus
>> code could just get the memory size.
>>

You can get memory checkpoint stats for each iteration - like
number of pages dirtied, size of data actually transmitted after
compression (including headers, etc),
time to checkpoint, etc.

The attached patch (for xen-4.1.2) will give you the memory checkpoint
stats for each checkpoint and
can be easily parsed.

shriram

Attachment: 04_stats_fix.patch
Description: Binary data

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