[libvirt] [PATCH v2 21/25] qemu: backup: Implement stats gathering while the job is running

[Eric Blake]

On 12/3/19 11:17 AM, Peter Krempa wrote:
> We can use the output of 'query-jobs' to figure out some useful
> information about a backup job. That is progress in case of a push job
> and scratch file use in case of a pull job.

[I still need to finish my review on 20, but this one's easier to knock 
out in the short term]

> 
> Add a worker which will total up the data and call it from
> qemuDomainGetJobStatsInternal.
> 
> Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> ---


> +static void
> +qemuBackupGetJobInfoStatsUpdateOne(virDomainObjPtr vm,

> +
> +    if (push) {
> +        stats->total += monblockjob->progressTotal;
> +        stats->transferred += monblockjob->progressCurrent;
> +    } else {
> +        stats->tmp_used += monblockjob->progressCurrent;
> +        stats->tmp_total += monblockjob->progressTotal;
> +    }

I don't know what qemu reports for the job used/total on the temp image 
(I guess the total is the guest-visible disk size?) but this reporting 
is reasonable enough for now.

This patch looks fine, so:
Reviewed-by: Eric Blake <eblake at redhat.com>

Still, seeing it made me wonder - when I first wrote the bitmap code, I 
added flag VIR_DOMAIN_CHECKPOINT_XML_SIZE for grabbing the current size 
of a bitmap, but disabled the qemu implementation of it at the last 
minute when committing the Checkpoint API because the monitor actions I 
used to get at it before -blockdev was not sane.  But I don't see it 
supported anywhere in this series.  The progress stats of a backup job 
are similar, but at some point, we do need to get a followup patch that 
gets size estimation from a bitmap prior to starting the backup back to 
viability.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org