Return-Path: In-Reply-To: <20090724184429.GA16811@fieldses.org> References: <200907231510.LAA43979@snowhite.cis.uoguelph.ca> <2CFD9099-9CE1-479D-99D0-80C4E5FA58F4@netapp.com> <20090724184429.GA16811@fieldses.org> Date: Fri, 24 Jul 2009 15:32:47 -0400 Message-ID: Subject: Re: nfs4 write delegation status From: "David V. Cloud" To: "J. Bruce Fields" Cc: Andy Adamson , linux-nfs@vger.kernel.org, erveith@de.ibm.com, nfsv4@linux-nfs.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============0527362971==" Sender: nfsv4-bounces@linux-nfs.org Errors-To: nfsv4-bounces@linux-nfs.org MIME-Version: 1.0 List-ID: --===============0527362971== Content-Type: multipart/alternative; boundary=0016367ed50846d437046f78ab29 --0016367ed50846d437046f78ab29 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit A simple one could be found in the following paper, http://www.usenix.org/events/fast07/tech/full_papers/gulati/gulati_html/nache.html -David On Fri, Jul 24, 2009 at 2:44 PM, J. Bruce Fields wrote: > On Thu, Jul 23, 2009 at 02:11:46PM -0400, Andy Adamson wrote: > > > > On Jul 23, 2009, at 11:10 AM, Rick Macklem wrote: > > > >>>> I really don't want to enable write delegations until we figure > >>>> out how > >>>> to enforce them correctly against local (non-nfs) users of the > >>>> exported > >>>> filesystem as well. In addition to breaking delegations on read > >>>> opens, > >>>> that means breaking delegations or doing a cb_getattr on > >>>> operations like > >>>> stat. > >>> > >>> do you know whether there are local FS where the maintainers at > >>> least plan > >>> to incorporate delegations? > >> > >> I'm not a Linux guy, so I'm not familiar with the internal structure, > >> but... > >> in general, I don't think the problem is with local file systems. > >> Usually > >> the problem is with local system call access. For example, if a > >> process running locally on the server opens a file, the delegation > >> should > >> be recalled, so that changes done locally on the client get flushed > >> back > >> to the server. Also, a write delegation allows a client to do byte > >> range > >> locking locally in the client, so the write delegation needs to be > >> recalled before anything gets a byte range lock locally in the server. > > > > The delegation implementation on the Linux server uses the vfs lease > > subsystem, and so is integrated with local access - conflicting opens > > done locally do recall delegations. But the last time I looked, the > > lease subsystem is not complete as it doesn't recall leases (nor > > delegations) on remove, rename, etc. Another problem is that while write > > delegations improve performance for certain workloads, they kill > > performance for others. > > Are there any published results yet with real workloads? > > --b. > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > --0016367ed50846d437046f78ab29 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable A simple one could be found in the following paper,

http://www.usenix.org/events/fast07/tech/full_papers/gulati/gulati_= html/nache.html

-David

On Fri, Jul 24, 2009 a= t 2:44 PM, J. Bruce Fields <bfields@fieldses.org> wrote:

On Thu, Jul 23, 2009 at 02:11:46PM -0400,= Andy Adamson wrote:
>
> On Jul 23, 2009, at 11:10 AM, Rick Macklem wrote:
>
>>>> I really don't want to enable write delegations until we f= igure
>>>> out how
>>>> to enforce them correctly against local (non-nfs) users of= the
>>>> exported
>>>> filesystem as well. In addition to breaking delegati= ons on read
>>>> opens,
>>>> that means breaking delegations or doing a cb_getattr on >>>> operations like
>>>> stat.
>>>
>>> do you know whether there are local FS where the maintainers a= t
>>> least plan
>>> to incorporate delegations?
>>
>> I'm not a Linux guy, so I'm not familiar with the internal structu= re,
>> but...
>> in general, I don't think the problem is with local file systems.<= br> >> Usually
>> the problem is with local system call access. For example, if a >> process running locally on the server opens a file, the delegation=
>> should
>> be recalled, so that changes done locally on the client get flushe= d
>> back
>> to the server. Also, a write delegation allows a client to do byte=
>> range
>> locking locally in the client, so the write delegation needs to be=
>> recalled before anything gets a byte range lock locally in the ser= ver.
>
> The delegation implementation on the Linux server uses the vfs lease > subsystem, and so is integrated with local access - conflicting opens<= br> > done locally do recall delegations. But the last time I looked, = the
> lease subsystem is not complete as it doesn't recall leases (nor
> delegations) on remove, rename, etc. Another problem is that while wri= te
> delegations improve performance for certain workloads, they kill
> performance for others.

Are there any published results yet with real workloads?

--b.

--
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the body of a message to major= domo@vger.kernel.org
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