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

[Xiao Guangrong]

On 06/05/2018 06:31 AM, Eric Blake wrote:
> On 06/04/2018 04:55 AM, address@hidden wrote:
> > From: Xiao Guangrong <address@hidden>
> >
> > Then the uses can adjust the parameters based on this info
> >
> > Currently, it includes:
> > pages: amount of pages compressed and transferred to the target VM
> > busy: amount of count that no free thread to compress data
> > busy-rate: rate of thread busy
> > reduced-size: amount of bytes reduced by compression
> > compression-rate: rate of compressed size
> >
> > Signed-off-by: Xiao Guangrong <address@hidden>
> > ---
>
> > +++ b/qapi/migration.json
> > @@ -72,6 +72,26 @@
> >              'cache-miss': 'int', 'cache-miss-rate': 'number',
> >              'overflow': 'int' } }
> > +##
> > +# @CompressionStats:
> > +#
> > +# Detailed compression migration statistics
>
> Sounds better as s/compression migration/migration compression/

Indeed.

> > +#
> > +# @pages: amount of pages compressed and transferred to the target VM
> > +#
> > +# @busy: amount of count that no free thread to compress data
>
> Not sure what was meant, maybe:
>
> @busy: count of times that no free thread was available to compress data

Yup, that's better.

> > +#
> > +# @busy-rate: rate of thread busy
>
> In what unit? pages per second?

It's calculated by:
   pages-directly-posted-out-without-compression / total-page-posted-out

> > +#
> > +# @reduced-size: amount of bytes reduced by compression
> > +#
> > +# @compression-rate: rate of compressed size
>
> In what unit?

It's calculated by:
   size-posted-out-after-compression / (compressed-page * page_size, i.e, that 
is
the raw data without compression)

> > +#
> > +##
>
> Missing a 'Since: 3.0' tag

Wow, directly upgrade to 3.0, big step. :-)
Will add this tag in the next version.

> > +{ 'struct': 'CompressionStats',
> > +  'data': {'pages': 'int', 'busy': 'int', 'busy-rate': 'number',
> > +       'reduced-size': 'int', 'compression-rate': 'number' } }
> > +
> >   ##
> >   # @MigrationStatus:
> >   #
> > @@ -169,6 +189,8 @@
> >   #           only present when the postcopy-blocktime migration capability
> >   #           is enabled. (Since 2.13)
>
> Pre-existing - we need to fix this 2.13 to be 3.0 (if it isn't already fixed)

I should re-sync the repo before making patches next time.

> >   #
> > +# @compression: compression migration statistics, only returned if compression
> > +#           feature is on and status is 'active' or 'completed' (Since 2.14)
>
> There will not be a 2.14 (for that matter, not even a 2.13).  The next release 
> is 3.0.

Okay, will fix.