From: Chuck Lever <chuck.lever@oracle.com>
To: Dai Ngo <dai.ngo@oracle.com>,
Benjamin Coddington <bcodding@hammerspace.com>
Cc: jlayton@kernel.org, neilb@ownmail.net, okorniev@redhat.com,
tom@talpey.com, hch@lst.de, alex.aring@gmail.com,
viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-nfs@vger.kernel.org
Subject: Re: [Patch 0/2] NFSD: Fix server hang when there are multiple layout conflicts
Date: Tue, 11 Nov 2025 10:34:04 -0500 [thread overview]
Message-ID: <5f014677-42c4-4638-a2ef-a1f285977ff4@oracle.com> (raw)
In-Reply-To: <e38104d7-1c2e-4791-aa78-d4458233dcb6@oracle.com>
On 11/11/25 10:24 AM, Dai Ngo wrote:
>>
>> Last thought (for now): I think Neil has some work for dynamic knfsd
>> thread
>> count.. or Jeff? (I am having trouble finding it) Would that work around
>> this problem?
>
> This would help, and I prefer this route rather than rework __break_lease
> to return EAGAIN/jukebox while the server recalling the layout.
Jeff is looking at continuing Neil's work in this area.
Adding more threads, IMHO, is not a good long term solution for this
particular issue. There's no guarantee that the server won't get stuck
no matter how many threads are created, and practically speaking, there
are only so many threads that can be created before the server goes
belly up. Or put another way, there's no way to formally prove that the
server will always be able to make forward progress with this solution.
We want NFSD to have a generic mechanism for deferring work so that an
nfsd thread never waits more than a few dozen milliseconds for anything.
This is the tactic NFSD uses for delegation recalls, for example.
--
Chuck Lever
next prev parent reply other threads:[~2025-11-11 15:34 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-06 17:05 [Patch 0/2] NFSD: Fix server hang when there are multiple layout conflicts Dai Ngo
2025-11-06 17:05 ` [PATCH 1/2] locks: Introduce lm_breaker_timedout op to lease_manager_operations Dai Ngo
2025-11-07 13:26 ` Christoph Hellwig
2025-11-07 16:58 ` Dai Ngo
2025-11-06 17:05 ` [PATCH 2/2] NFSD: Fix server hang when there are multiple layout conflicts Dai Ngo
2025-11-07 13:29 ` Christoph Hellwig
2025-11-07 17:01 ` Dai Ngo
2025-11-07 13:30 ` [Patch 0/2] " Christoph Hellwig
2025-11-09 18:34 ` Benjamin Coddington
2025-11-11 15:24 ` Dai Ngo
2025-11-11 15:34 ` Chuck Lever [this message]
2025-11-11 15:36 ` Christoph Hellwig
2025-11-11 15:43 ` Dai Ngo
2025-11-11 15:53 ` Chuck Lever
2025-11-11 15:45 ` Jeff Layton
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