Re: [GIT PULL] (xen) stable/for-jens-3.2 - blkback and blkfront patches for 3.2

Li Dongyang
2011-09-25T02:37:46Z

seems my mail did not reach the mailing list?

On Fri, Sep 23, 2011 at 11:38 PM, Li Dongyang <lidongyang@novell.com> wrote:
> On Friday, September 23, 2011, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
>> On Thu, Sep 22, 2011 at 09:05:17PM +1000, Li Dongyang wrote:
>>> On Thursday, September 22, 2011, Konrad Rzeszutek Wilk <
>>> konrad.wilk@oracle.com> wrote:
>>> > On Wed, Sep 21, 2011 at 11:17:32AM -0400, Christoph Hellwig wrote:
>>> >> On Wed, Sep 21, 2011 at 11:09:55AM -0400, Konrad Rzeszutek Wilk wrote:
>>> >> > Hey Jens,
>>> >> >
>>> >> > Please pull the following git tree in your 3.2 drivers tree:
>>> >> >
>>> >> >  git pull git://oss.oracle.com/git/kwilk/xen.git stable/for-jens-3.2
>>> >> >
>>> >> > which has an exciting new feature - the discard ('feature-discard')
>>> >> > aka TRIM/UNMAP. Now they can be passed from the guest to the
>>> >> > backend.
>>> >>
>>> >> What is the design of them?  Do you provide the 'discard zeroes data'
>>> >> flag (mandatory for any kind of relible operation) and 'discard
>>> >
>>> > Hmm, not sure what that is. Is that REQ_SECURE, err
>>> > BLKDEV_DISCARD_SECURE?
>>> > If so then not in this patchset - but it does not seem like it would
>>> dificult
>>> > to add that in? Li, what do you think?
>>> We deal the discard with 2 ways in the backend depend on what the guest
>>> is
>>> using:
>>> punch the hole on the image, to save some disk usage,
>>> or redirect the discard request to phy device.
>>> for the hole punching case, we are already DISCARD_SECURE,
>>> for the phy dev case, we could add the flag and pass it from blkfront to
>>> blkback, and yes
>>> That's not difficult, could be added later.
>>
>> Li, could you implement it please  - on top of the 'stable/for-jens-3.2'
>> patch queue ?
>> If it would not be too much trouble of course.
> Yeah I'd like to, but am on a vacation to Australia, nothing with me except
> an iPad,
> and I'll be back on 7th next month, so I gonna sent a patch after that,
> Thanks.
>>
>>> >
>>> >> granularity / alignment' tunables (very useful)?
>>> >
>>> > The discard granularity/alignment are certainly there. But they are
>>> > just
>>> > one way (backend tells the guest what they are). Should they be
>>> > more tunable (frontend tells the backend what the values ought to be?)
>>> >
>>> Yes, plz tell more about tunable granularity and alignment, and we can
>>> add
>>> that later,
>>> Thanks a lot
>>> > Li, did I miss anything in my response?
>>> >
>>