Re: [Nbd] [PATCH] proto: add 'shift' extension.

["Denis V. Lunev" <den@...2319...>]

On 09/27/2016 08:04 PM, Paolo Bonzini wrote:
>
> On 27/09/2016 15:28, Denis V. Lunev wrote:
>> On 09/27/2016 03:07 PM, Paolo Bonzini wrote:
>>> ----- Original Message -----
>>>> From: "Denis V. Lunev" <den@...2319...>
>>>> To: "Paolo Bonzini" <pbonzini@...696...>
>>>> Cc: "Vladimir Sementsov-Ogievskiy" <vsementsov@...2319...>, qemu-devel@...530..., qemu-block@...530...,
>>>> nbd-general@lists.sourceforge.net, alex@...872..., eblake@...696..., kwolf@...696..., stefanha@...696...,
>>>> w@...112...
>>>> Sent: Tuesday, September 27, 2016 12:25:54 PM
>>>> Subject: Re: [PATCH] proto: add 'shift' extension.
>>>>
>>>> On 09/27/2016 01:15 PM, Paolo Bonzini wrote:
>>>>>> We could go in a different direction and export flag
>>>>>> 'has_zero_init' which will report that the storage is
>>>>>> initialized with all zeroes at the moment. In this
>>>>>> case mirroring code will not fall into this
>>>>>> branch.
>>>>> Why don't you add the zero_init flag to QEMU's NBD driver instead?
>>>> for all cases without knowing real backend on the server side?
>>>> I think this would be wrong.
>>> Add it to the command line, and leave it to libvirt or the user to
>>> pass "-drive file.driver=nbd,...,file.zero-init=on".
>> I have started with something very similar for 'drive-mirror' command.
>> We have added additional flag for this to improve migration speed
>> and this was rejected.
> You can add it through the filename path too, through a URI option
> "nbd://...?zero-init=on".
>
> Paolo
ha, cool idea! Thanks!

Den