From: Christoph Hellwig <hch@lst.de>
To: Chuck Lever <cel@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
Trond Myklebust <trondmy@kernel.org>,
Anna Schumaker <anna@kernel.org>,
linux-nfs@vger.kernel.org
Subject: Re: add a LRU for delegations
Date: Wed, 7 Jan 2026 17:22:02 +0100 [thread overview]
Message-ID: <20260107162202.GA23066@lst.de> (raw)
In-Reply-To: <0b0b21c1-0bfd-4e2e-9deb-f368a66f5e9c@app.fastmail.com>
On Wed, Jan 07, 2026 at 10:18:04AM -0500, Chuck Lever wrote:
> > currently the NFS client is rather inefficient at managing delegations
> > not associated with an open file. If the number of delegations is above
> > the watermark, the delegation for a free file is immediately returned,
> > even if delegations that were unused for much longer would be available.
> > Also the periodic freeing marks delegations as not referenced for return,
> > even if the file was open and thus force the return on close.
> >
> > This series reworks the code to introduce an LRU and return the least
> > used delegations instead.
>
> I'm curious if you tried other methodologies like LFU to decide which
> delegation to return?
Not really. LFU I guess means least frequently used. That would
imply tracking usage frequency, and rotating a list of other lookup
structure a lot. The first is something not really provided in the
delegation code, and the latter tends to be really horrible for in
terms of cache dirtying.
next prev parent reply other threads:[~2026-01-07 16:22 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-07 7:26 add a LRU for delegations Christoph Hellwig
2026-01-07 7:26 ` [PATCH 01/24] NFS: remove __nfs_client_for_each_server Christoph Hellwig
2026-01-07 7:26 ` [PATCH 02/24] NFS: remove nfs_client_mark_return_unused_delegation_types Christoph Hellwig
2026-01-07 7:26 ` [PATCH 03/24] NFS: remove nfs_client_mark_return_all_delegations Christoph Hellwig
2026-01-07 7:26 ` [PATCH 04/24] NFS: remove the NULL inode check in nfs4_inode_return_delegation_on_close Christoph Hellwig
2026-01-07 7:26 ` [PATCH 05/24] NFS: remove nfs_inode_detach_delegation Christoph Hellwig
2026-01-07 7:26 ` [PATCH 06/24] NFS: remove nfs_start_delegation_return Christoph Hellwig
2026-01-07 7:26 ` [PATCH 07/24] NFS: assert rcu_read_lock is held in nfs_start_delegation_return_locked Christoph Hellwig
2026-01-07 7:26 ` [PATCH 08/24] NFS: drop the _locked postfix from nfs_start_delegation_return Christoph Hellwig
2026-01-07 7:27 ` [PATCH 09/24] NFS: remove NFS_DELEGATION_INODE_FREEING Christoph Hellwig
2026-01-07 7:27 ` [PATCH 10/24] NFS: open code nfs_delegation_need_return Christoph Hellwig
2026-01-07 7:27 ` [PATCH 11/24] NFS: remove nfs_free_delegation Christoph Hellwig
2026-01-07 7:27 ` [PATCH 12/24] NFS: rewrite nfs_delegations_present in terms of nr_active_delegations Christoph Hellwig
2026-01-07 7:27 ` [PATCH 13/24] NFS: move delegation lookup into can_open_delegated Christoph Hellwig
2026-01-07 7:27 ` [PATCH 14/24] NFS: return bool from nfs_detach_delegation{,_locked} Christoph Hellwig
2026-01-07 7:27 ` [PATCH 15/24] NFS: move the deleg_cur check out of nfs_detach_delegation_locked Christoph Hellwig
2026-01-07 7:27 ` [PATCH 16/24] NFS: simplify the detached delegation check in update_open_stateid Christoph Hellwig
2026-01-07 7:27 ` [PATCH 17/24] NFS: take a delegation reference in nfs4_get_valid_delegation Christoph Hellwig
2026-01-07 7:27 ` [PATCH 18/24] NFS: don't consume a delegation reference in nfs_end_delegation_return Christoph Hellwig
2026-01-07 7:27 ` [PATCH 19/24] NFS: use refcount_inc_not_zero nfs_start_delegation_return Christoph Hellwig
2026-01-07 7:27 ` [PATCH 20/24] NFS: use a local RCU critical section in nfs_start_delegation_return Christoph Hellwig
2026-01-07 7:27 ` [PATCH 21/24] NFS: reformat nfs_mark_delegation_revoked Christoph Hellwig
2026-01-07 7:27 ` [PATCH 22/24] NFS: add a separate delegation return list Christoph Hellwig
2026-01-25 13:30 ` Chris Mason
2026-01-26 6:06 ` Christoph Hellwig
2026-01-07 7:27 ` [PATCH 23/24] NFS: return delegations from the end of a LRU when over the watermark Christoph Hellwig
2026-01-07 7:27 ` [PATCH 24/24] NFS: make nfs_mark_return_unreferenced_delegations less aggressive Christoph Hellwig
2026-01-07 15:18 ` add a LRU for delegations Chuck Lever
2026-01-07 16:22 ` Christoph Hellwig [this message]
2026-01-07 19:22 ` Sagi Grimberg
2026-01-08 13:46 ` Christoph Hellwig
2026-01-09 0:13 ` Sagi Grimberg
2026-01-08 14:34 ` Chuck Lever
2026-01-08 15:35 ` Christoph Hellwig
2026-01-09 0:30 ` Sagi Grimberg
2026-01-09 1:07 ` Trond Myklebust
2026-01-11 7:46 ` Sagi Grimberg
2026-01-15 16:24 ` Christoph Hellwig
2026-01-21 20:42 ` Anna Schumaker
-- strict thread matches above, loose matches on Subject: below --
2025-12-18 5:56 Christoph Hellwig
2025-12-18 5:50 Christoph Hellwig
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