Re: [Qemu-devel] [PATCH v10 08/10] migration: postcopy_blocktime documentation

[Dr. David Alan Gilbert]

* Alexey Perevalov (address@hidden) wrote:
> On 09/21/2017 03:33 PM, Dr. David Alan Gilbert wrote:
> > * Alexey Perevalov (address@hidden) wrote:
> > > Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> > > Signed-off-by: Alexey Perevalov <address@hidden>
> > Although it does have my R-b it might be worth adding some clarification
> > that it's a measure of when *all* cpus are blocked and so isn't a
> > total measure of impact of postcopy (when blocking some of them).
> yes, maybe additional clarification is necessary.
> now we have both values:
> {"return": {"postcopy-blocktime": 5691, "status": "completed",
> "postcopy-vcpu-blocktime": [7671, 6388]}}
> where postcopy-blocktime is for *all* and postcopy-vcpu-blocktime is per
> vCPU,
> it's really worth to describe it, like:
> 
> Blocktime is a postcopy live migration metric, intended to show
> how long the vCPU was in state of interruptible sleep due to pagefault.
> That metric is calculated both for all vCPUs as overlapped value, and
> separately for each vCPU. These values are calculated on destination side.
> To enable postcopy blocktime calculation, enter following command on 
> destination
> monitor:
> 
> migrate_set_capability postcopy-blocktime on
> 
> Postcopy blocktime can be retrieved by query-migrate qmp command.
> postcopy-blocktime value of qmp command will show overlapped blocking time 
> for all vCPU,
> postcopy-vcpu-blocktime will show list of blocking time per vCPU.


Yep that seems OK.

Dave

> -- 
> Best regards,
> Alexey Perevalov
> 
> > 
> > Dave
> > 
> > > ---
> > >   docs/devel/migration.txt | 10 ++++++++++
> > >   1 file changed, 10 insertions(+)
> > > 
> > > diff --git a/docs/devel/migration.txt b/docs/devel/migration.txt
> > > index 1b940a8..4b625ca 100644
> > > --- a/docs/devel/migration.txt
> > > +++ b/docs/devel/migration.txt
> > > @@ -402,6 +402,16 @@ will now cause the transition from precopy to 
> > > postcopy.
> > >   It can be issued immediately after migration is started or any
> > >   time later on.  Issuing it after the end of a migration is harmless.
> > > +Blocktime is a postcopy live migration metric, intended to show
> > > +how long the vCPU was in state of interruptable sleep due to pagefault.
> > > +This value is calculated on destination side.
> > > +To enable postcopy blocktime calculation, enter following command on 
> > > destination
> > > +monitor:
> > > +
> > > +migrate_set_capability postcopy-blocktime on
> > > +
> > > +Postcopy blocktime can be retrieved by query-migrate qmp command.
> > > +
> > >   Note: During the postcopy phase, the bandwidth limits set using
> > >   migrate_set_speed is ignored (to avoid delaying requested pages that
> > >   the destination is waiting for).
> > > -- 
> > > 1.9.1
> > > 
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
> > 
> > 
> > 
> 
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK