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Date:   Tue, 19 Apr 2022 15:57:37 -0400
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Subject: Re: [PATCH v4 0/7] Intruduce nfsrahead
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To:     Thiago Becker <tbecker@redhat.com>, linux-nfs@vger.kernel.org
Cc:     trond.myklebust@hammerspace.com, anna.schumaker@netapp.com,
        kolga@netapp.com
References: <20220401153208.3120851-1-tbecker@redhat.com>
From:   Steve Dickson <steved@redhat.com>
In-Reply-To: <20220401153208.3120851-1-tbecker@redhat.com>
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On 4/1/22 11:32 AM, Thiago Becker wrote:
> Recent changes in the linux kernel caused NFS readahead to default to
> 128 from the previous default of 15 * rsize. This causes performance
> penalties to some read-heavy workloads, which can be fixed by
> tuning the readahead for that given mount.
> 
> Specifically, the read troughput on a sec=krb5p mount drops by 50-75%
> when comparing the default readahead with a readahead of 15360.
> 
> Previous discussions:
> https://lore.kernel.org/linux-nfs/20210803130717.2890565-1-trbecker@gmail.com/
> I attempted to add a non-kernel option to mount.nfs, and it was
> rejected.
> 
> https://lore.kernel.org/linux-nfs/20210811171402.947156-1-trbecker@gmail.com/
> Attempted to add a mount option to the kernel, rejected as well.
> 
> I had started a separate tool to set the readahead of BDIs, but the
> scope is specifically for NFS, so I would like to get the community
> feeling for having this in nfs-utils.
> 
> This patch series introduces nfs-readahead-udev, a utility to
> automatically set NFS readahead when NFS is mounted. The utility is
> triggered by udev when a new BDI is added, returns to udev the value of
> the readahead that should be used.
> 
> The tool currently supports setting read ahead per mountpoint, nfs major
> version, or by a global default value.
> 
> v2:
>      - explain the motivation
> 
> v3:
>      - adopt already available facilities
>      - nfsrahead is now configured in nfs.conf
> 
> v4:
>      - retry getting the device if it fails
>      - assorted fixes and improvements
> 
> Thiago Becker (7):
>    Create nfsrahead
>    nfsrahead: configure udev
>    nfsrahead: only set readahead for nfs devices.
>    nfsrahead: add logging
>    nfsrahead: get the information from the config file.
>    nfsrahead: User documentation
>    nfsrahead: retry getting the device if it fails.
> 
>   .gitignore                      |   2 +
>   configure.ac                    |   1 +
>   systemd/nfs.conf.man            |  11 ++
>   tools/Makefile.am               |   2 +-
>   tools/nfsrahead/99-nfs.rules.in |   1 +
>   tools/nfsrahead/Makefile.am     |  16 +++
>   tools/nfsrahead/main.c          | 183 ++++++++++++++++++++++++++++++++
>   tools/nfsrahead/nfsrahead.man   |  72 +++++++++++++
>   8 files changed, 287 insertions(+), 1 deletion(-)
>   create mode 100644 tools/nfsrahead/99-nfs.rules.in
>   create mode 100644 tools/nfsrahead/Makefile.am
>   create mode 100644 tools/nfsrahead/main.c
>   create mode 100644 tools/nfsrahead/nfsrahead.man
> 
Committed... (tag nfs-utils-2-6-2-rc4)

steved.