RE: [PATCH V7 mlx5-next 15/15] vfio: Extend the device migration protocol with PRE_COPY

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Tuesday, February 22, 2022 11:51 PM
> 
> On Tue, Feb 22, 2022 at 01:43:13AM +0000, Tian, Kevin wrote:
> 
> > > > > + * Drivers should attempt to return estimates so that initial_bytes +
> > > > > + * dirty_bytes matches the amount of data an immediate transition
> to
> > > > > STOP_COPY
> > > > > + * will require to be streamed.
> > > >
> > > > I didn't understand this requirement. In an immediate transition to
> > > > STOP_COPY I expect the amount of data covers the entire device
> > > > state, i.e. initial_bytes. dirty_bytes are dynamic and iteratively returned
> > > > then why we need set some expectation on the sum of
> > > > initial+round1_dity+round2_dirty+...
> > >
> > > "will require to be streamed" means additional data from this point
> > > forward, not including anything already sent.
> > >
> > > It turns into the estimate of how long STOP_COPY will take.
> >
> > I still didn't get the 'match' part. Why should the amount of data which
> > has already been sent match the additional data to be sent in STOP_COPY?
> 
> None of it is 'already been sent' the return values are always 'still
> to be sent'
> 

Reread the description:

+ * Drivers should attempt to return estimates so that initial_bytes +
+ * dirty_bytes matches the amount of data an immediate transition to STOP_COPY
+ * will require to be streamed.

I guess you intended to mean that when EITHER initial_bytes OR
dirty_bytes is read the returned value should match the amount 
of data as described above. It is "+" which confused me to think 
it as a sum of both numbers...

Thanks
Kevin




[Index of Archives]     [DMA Engine]     [Linux Coverity]     [Linux USB]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Greybus]

  Powered by Linux