Subject: Re: directory delegations
From:   "Bradley C. Kuszmaul" <bradley.kuszmaul@oracle.com>
To:     "J. Bruce Fields" <bfields@fieldses.org>
Cc:     linux-nfs@vger.kernel.org
References: <2065755c-f888-9c62-f6e5-f143d42c51ee@oracle.com>
 <20190402161116.GA2828@fieldses.org>
 <2f1f6582-3672-1361-4392-80cb1e62e19c@oracle.com>
Message-ID: <03576c76-abca-9e3c-bf58-5a2a22e8f999@oracle.com>
Date:   Tue, 2 Apr 2019 13:29:10 -0400
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I stand corrected.  Apparently there is no LOOKUP, so maybe read-only 
directory delegations don't help at all with untar.

-Bradley

On 4/2/19 1:26 PM, Bradley C. Kuszmaul wrote:
> My simple model of metadata operations is to untar something like the 
> linux sources.
>
> Each file incurs a LOOKUP, CREATE, SETATTR, and WRITE, each of which 
> is fairly high latency (even the WRITE ends up being done essentially 
> synchronously because tar closes the file after its write(2) call.)
>
> I guess directory delegations might save the cost of LOOKUP.
>
> Is there any hope for getting write delegations?
>
> What other steps might be possible?
>
> -Bradley
>
> On 4/2/19 12:11 PM, bfields@fieldses.org wrote:
>> On Mon, Apr 01, 2019 at 12:21:49PM -0400, Bradley C. Kuszmaul wrote:
>>> Hi, I'm the architect for Oracle's File Storage Service.   FSS is
>>> basically a big scalable NFS server that runs in Oracle's cloud.
>>>
>>> Our metadata operations have higher latency than a vanilla NFS
>>> server (e.g., a Linux NFS server serving a XFS stored on a block
>>> device), and we suspect that directory delegations would make a big
>>> performance improvement.
>>>
>>> I understand, however, that essentially no one implements directory
>>> delegations.
>>>
>>> Can anyone fill me in on the current thinking of the future of
>>> support for directory delegations in the Linux NFS client?
>> Maybe somebody else will speak up, but I don't know of any effort to
>> implement directory delegations.
>>
>> What metadata operations specifically are you worried about? The
>> directory delegations that are specified in RFC 5661 are read-only.
>> Which might explain some of the lack of interest.
>>
>> But there may be other steps that we could take to improve matters.
>>
>> --b.