Re: [PATCH 2/6] migration/multifd: Add zero pages and zero bytes counter to migration status interface.

[Peter Xu <peterx@redhat.com>]

On Wed, Feb 07, 2024 at 12:13:10PM +0800, Peter Xu wrote:
> On Tue, Feb 06, 2024 at 11:19:04PM +0000, Hao Xiang wrote:
> > This change extends the MigrationStatus interface to track zero pages
> > and zero bytes counter.
> > 
> > Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>

I'll need to scratch this, sorry..

The issue is I forgot we have "duplicate" which is exactly "zero
page"s.. See:

    info->ram->duplicate = stat64_get(&mig_stats.zero_pages);

If you think the name too confusing and want a replacement, maybe it's fine
and maybe we can do that.  Then we can keep this zero page counter
introduced, reporting the same value as duplicates, then with a follow up
patch to deprecate "duplicate" parameter.  See an exmaple on how to
deprecate in 7b24d326348e1672.

One thing I'm not sure is whether Libvirt will be fine on losing
"duplicates" after 2+ QEMU major releases.  Copy Jiri for this.  My
understanding is that Libvirt should be keeping an eye on deprecation list
and react, but I'd like to double check..

Or we can keep using "duplicates", but I agree it just reads weird..

Thanks,

-- 
Peter Xu