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From: bfields@fieldses.org (J. Bruce Fields)
To: "J. Bruce Fields" <bfields@redhat.com>
Cc: Jeff Layton <jlayton@redhat.com>,
	linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Trond Myklebust <trondmy@hammerspace.com>,
	David Howells <dhowells@redhat.com>, Tejun Heo <tj@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>, Shaohua Li <shli@fb.com>,
	Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 0/7] Eliminate delegation self-conflicts
Date: Fri, 15 Feb 2019 11:35:14 -0500
Message-ID: <20190215163514.GA22354@fieldses.org> (raw)
In-Reply-To: <20190211155803.GA28714@parsley.fieldses.org>

On Mon, Feb 11, 2019 at 10:58:04AM -0500, J. Bruce Fields wrote:
> On Sat, Feb 09, 2019 at 07:43:54AM -0500, Jeff Layton wrote:
> > On Fri, 2019-02-08 at 15:10 -0500, J. Bruce Fields wrote:
> > > From: "J. Bruce Fields" <bfields@redhat.com>
> > > 
> > > These patches allow NFSv4 clients holding delegations to keep them when
> > > the operation that would break a delegation comes from the same client.
> > > 
> > > To do that, we somehow need to pass the identity of the
> > > delegation-breaker down through the VFS.
> > > 
> > > This series uses the tgid, a solution suggested by Trond.  To do that we
> > > need nfsd tasks to share the same tgid.  I do that by extending the
> > > kthread code slightly to allow knfsd to run the kthreadd main loop in a
> > > task of its own, and spawn its server threads off of that task.
> ...
> > Nice work! I like the basic idea, the changes seem to be well-organized, 
> > and the tgid semantics are clear and make sense.
> > 
> > Would this preclude us from moving to a workqueue-based model for knfsd
> > later? It's likely to still be worth it, but it'd be good to understand
> > the potential drawbacks.
> 
> I was wondering about that too, but I haven't looked into it yet.
> Workqueues look a lot more complicated than kthreads.

I spent some time staring, and...  I still don't really understand the
workqueue code.  But if this kthread_group[*] code is acceptable than I
can't see why it shouldn't be possible to create a workqueue whose work
items are all handled by threads spawned form the same kthread_group.

--b.

[*] Open to suggestions of better names.

      reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-08 20:10 J. Bruce Fields
2019-02-08 20:10 ` [PATCH 1/7] kthreads: minor kthreadd refactoring J. Bruce Fields
2019-02-08 20:10 ` [PATCH 2/7] kthreads: Simplify tsk_fork_get_node J. Bruce Fields
2019-02-08 20:10 ` [PATCH 3/7] kthreads: allow multiple kthreadd's J. Bruce Fields
2019-03-12 20:01   ` bfields
2019-02-08 20:10 ` [PATCH 4/7] kthreads: allow cloning threads with different flags J. Bruce Fields
2019-02-08 20:10 ` [PATCH 5/7] rpc: separate out body of svc_start_kthreads J. Bruce Fields
2019-02-08 20:10 ` [PATCH 6/7] rpc: move rpc server threads into their own thread group J. Bruce Fields
2019-02-08 20:10 ` [PATCH 7/7] nfsd: ignore delegation self-conflicts J. Bruce Fields
2019-02-09 12:43 ` [PATCH 0/7] Eliminate " Jeff Layton
2019-02-11 15:58   ` J. Bruce Fields
2019-02-15 16:35     ` bfields [this message]

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