Re: [Qemu-devel] [PATCH 05/12] migration: show the statistics of compression

[Xiao Guangrong]

On 07/17/2018 03:01 AM, Dr. David Alan Gilbert wrote:
> * Xiao Guangrong (address@hidden) wrote:
> > On 06/14/2018 12:25 AM, Dr. David Alan Gilbert wrote:
> >   }
> > > >    static void migration_bitmap_sync(RAMState *rs)
> > > > @@ -1412,6 +1441,9 @@ static void flush_compressed_data(RAMState *rs)
> > > >            qemu_mutex_lock(&comp_param[idx].mutex);
> > > >            if (!comp_param[idx].quit) {
> > > >                len = qemu_put_qemu_file(rs->f, comp_param[idx].file);
> > > > +            /* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
> > > > +            compression_counters.reduced_size += TARGET_PAGE_SIZE - len + 8;
> > >
> > > I think I'd rather save just len+8 rather than than the subtraction.
> > Hmmmmmm, is this what you want?
> >        compression_counters.reduced_size += len - 8;
> >
> > Then calculate the real reduced size in populate_ram_info() where we return this
> > info to the user:
> >        info->compression->reduced_size = compression_counters.pages * PAGE_SIZE 
> > - compression_counters.reduced_size;
> >
> > Right?
>
> I mean I'd rather see the actual size presented to the user rather than
> the saving compared to uncompressed.

These statistics are used to help people to see whether compression works 
efficiently or not,
so maybe reduced-size is more straightforward?　:)