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References: <20220223211305.296816-1-trondmy@kernel.org>
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From:   David Wysochanski <dwysocha@redhat.com>
Date:   Thu, 24 Feb 2022 10:07:18 -0500
Message-ID: <CALF+zOm0X8oH2=QbpdDJzCvZLq5qb2ygsuQAUo4e4P242Px+dQ@mail.gmail.com>
Subject: Re: [PATCH v7 00/21] Readdir improvements
To:     trondmy@kernel.org
Cc:     linux-nfs <linux-nfs@vger.kernel.org>
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On Wed, Feb 23, 2022 at 4:24 PM <trondmy@kernel.org> wrote:
>
> From: Trond Myklebust <trond.myklebust@hammerspace.com>
>
> The current NFS readdir code will always try to maximise the amount of
> readahead it performs on the assumption that we can cache anything that
> isn't immediately read by the process.
> There are several cases where this assumption breaks down, including
> when the 'ls -l' heuristic kicks in to try to force use of readdirplus
> as a batch replacement for lookup/getattr.
>
> This series also implement Ben's page cache filter to ensure that we can
> improve the ability to share cached data between processes that are
> reading the same directory at the same time, and to avoid live-locks
> when the directory is simultaneously changing.
>
> --
> v2: Remove reset of dtsize when NFS_INO_FORCE_READDIR is set
> v3: Avoid excessive window shrinking in uncached_readdir case
> v4: Track 'ls -l' cache hit/miss statistics
>     Improved algorithm for falling back to uncached readdir
>     Skip readdirplus when files are being written to
> v5: bugfixes
>     Skip readdirplus when the acdirmax/acregmax values are low
>     Request a full XDR buffer when doing READDIRPLUS
> v6: Add tracing
>     Don't have lookup request readdirplus when it won't help
> v7: Implement Ben's page cache filter
>     Reduce the use of uncached readdir
>     Change indexing of the page cache to improve seekdir() performance.
>
> Trond Myklebust (21):
>   NFS: constify nfs_server_capable() and nfs_have_writebacks()
>   NFS: Trace lookup revalidation failure
>   NFS: Use kzalloc() to avoid initialising the nfs_open_dir_context
>   NFS: Calculate page offsets algorithmically
>   NFS: Store the change attribute in the directory page cache
>   NFS: If the cookie verifier changes, we must invalidate the page cache
>   NFS: Don't re-read the entire page cache to find the next cookie
>   NFS: Adjust the amount of readahead performed by NFS readdir
>   NFS: Simplify nfs_readdir_xdr_to_array()
>   NFS: Reduce use of uncached readdir
>   NFS: Improve heuristic for readdirplus
>   NFS: Don't ask for readdirplus unless it can help nfs_getattr()
>   NFSv4: Ask for a full XDR buffer of readdir goodness
>   NFS: Readdirplus can't help lookup for case insensitive filesystems
>   NFS: Don't request readdirplus when revalidation was forced
>   NFS: Add basic readdir tracing
>   NFS: Trace effects of readdirplus on the dcache
>   NFS: Trace effects of the readdirplus heuristic
>   NFS: Convert readdir page cache to use a cookie based index
>   NFS: Fix up forced readdirplus
>   NFS: Remove unnecessary cache invalidations for directories
>
>  fs/nfs/dir.c           | 450 ++++++++++++++++++++++++-----------------
>  fs/nfs/inode.c         |  46 ++---
>  fs/nfs/internal.h      |   4 +-
>  fs/nfs/nfs3xdr.c       |   7 +-
>  fs/nfs/nfs4proc.c      |   2 -
>  fs/nfs/nfs4xdr.c       |   6 +-
>  fs/nfs/nfstrace.h      | 122 ++++++++++-
>  include/linux/nfs_fs.h |  19 +-
>  8 files changed, 421 insertions(+), 235 deletions(-)
>
> --
> 2.35.1
>

I don't see this pushed this to your 'testing' branch, but I applied
manually after resetting at 3f58e709c162