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Message-ID: <309e27b9-da26-bcd0-dc55-1b63cb93203f@math.utexas.edu>
Date:   Fri, 4 Feb 2022 14:55:43 -0600
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Subject: Re: Cache flush on file lock
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To:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
References: <20220202014111.GA7467@hostway.ca>
 <4691F0AB-FCDB-49EF-B62B-51F135F692A5@oracle.com>
From:   Patrick Goetz <pgoetz@math.utexas.edu>
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On 2/2/22 13:55, Chuck Lever III wrote:
> 
> 
>> On Feb 1, 2022, at 8:41 PM, Simon Kirby <sim@hostway.ca> wrote:
>>
>> How far off would we be from write delegations happening here?
> 
> We are tracking a "feature request" for write delegation support
> in the Linux NFS server:
> 
> https://bugzilla.linux-nfs.org/show_bug.cgi?id=348
> 
> At this point the effort is not resourced. It's not clear how
> much benefit it would be.
> 

First shock is I thought write delegation was already supported.

But especially for users who have NFS mounted home directories, how 
could there not be a major performance benefit? To cite one example that 
has been a problem before (in particular, on Mac OSX clients with NFSv3 
home directories mounted from a linux fileserver), facilitating the 
firefox "awesome" bar, which writes to a SQLlite database in 
~/.mozilla/fireworks with alarming frequency in order to keep up the 
awesomeness.

This flat out didn't work previously unless you went to about:config and 
set

   storage.nfs_filesystem = true

Not at all sure how this changed the execution of firefox though.


> That said, it seems to me that your use case might benefit if
> the Linux NFS server offered a READ delegation for the SQLite
> database file even when it is open R/W. It might be appropriate
> if the server offered such a delegation when there are no other
> clients that have the file open for write or that hold write
> delegations.
> 
> Patches and performance data are, as always, welcome.
> 
> 
> --
> Chuck Lever
> 
> 
>