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Date:      Tue, 9 Jun 2026 10:02:25 -0700
From:      Bakul Shah <bakul@iitbombay.org>
To:        Rick Macklem <rick.macklem@gmail.com>
Cc:        Dan Shelton <dan.f.shelton@gmail.com>, freebsd-hackers@freebsd.org
Subject:   Re: BHYVE on NFSv4.2 filesystem?
Message-ID:  <725FEEE6-D75E-4D75-B464-008B2678120B@iitbombay.org>
In-Reply-To: <CAM5tNy4AO7JqXuKrWjR8ABVc4VhJR0ipicWbatA5w3BG2PXqxg@mail.gmail.com>
References:  <CAAvCNcAmVFUveVcvPBYN1Ph4eVbj3Nzta3aChBQj=WxON2NnKQ@mail.gmail.com> <CAAvCNcBdzu=2w78awKDGE2adQ0asF2ZyZWkYvaKRO2KdfuJ8tw@mail.gmail.com> <D9B72D33-469A-49E1-9C6F-0E0BCE4E9BFC@iitbombay.org> <CAAvCNcAqoL7JjQfQq-Z8pauuxNHWU90Hk0rMrRoA8u-tGAJ=bw@mail.gmail.com> <C5C7DD8C-3DC5-4CE1-A260-EB86A44F86BE@iitbombay.org> <CAM5tNy4AO7JqXuKrWjR8ABVc4VhJR0ipicWbatA5w3BG2PXqxg@mail.gmail.com>
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On Jun 9, 2026, at 8:49 AM, Rick Macklem <rick.macklem@gmail.com> wrote:
> 
> On Mon, May 18, 2026 at 3:39 PM Bakul Shah <bakul@iitbombay.org> wrote:
>> 
>> On May 18, 2026, at 2:26 PM, Dan Shelton <dan.f.shelton@gmail.com> wrote:
>>> 
>>> On Fri, 20 Feb 2026 at 01:21, Bakul Shah <bakul@iitbombay.org> wrote:
>>>> 
>>>> On Feb 19, 2026, at 11:45 AM, Dan Shelton <dan.f.shelton@gmail.com> wrote:
>>>>> 
>>>>> On Wed, 18 Feb 2026 at 22:45, Dan Shelton <dan.f.shelton@gmail.com> wrote:
>>>>>> 
>>>>>> Hello,
>>>>>> 
>>>>>> Has anyone tried a BHYVE with a disk as file on a NFSv4.2 mount?
>>>> 
>>>> Yes. [I tried this on a 15.0-RELEASE-p3 host, nfsv4.2 mounting
>>>> a filesystem from a 15.0-STABLE machine]
>>> 
>>> How about the performance? Is it better than iSCSI?
>> 
>> I don't know about iSCSI but comparing with p9fs:
>> 
>> Test1:
>> dd bs=1m count=4000 > /dev/null < large-file
>> 
>> nfsV3:
>> 32.3
>> 46.3
>> 51.3
>> 
>> nfsV4:
>> 129.1
>> 59.9
>> 48.8
>> 
>> p9fs:
>> 17.7
>> 17.5
>> 17.6
>> 
>> Test2:
>> find /usr/src/ > /dev/null
>> 
>> nfsV3:
>> 60.0
>> 39.0
>> 30.9
>> 
>> nfsV4:
>> 54.0
>> 17.9
>> 35.8
>> 
>> p9fs:
>> 6.9
>> 6.5
>> 6.6
>> 
>> 
>> So slower in all cases. In addition the variability in nfs numbers is concerning!
>> 
>> p9fs doesn't cache but nfs does, so anything cached is served much faster.
> At this time it is only a hunch, but I think this might help..
> https://datatracker.ietf.org/doc/draft-ietf-nfsv4-uncacheable-files/

Just to clarify, if data is cached, NFS is usually much faster;
but the above tests didn't have any caching effect. In general
caching can be a win but it is more that the 9p protocol *can't*
do caching - no way to specify cache invalidation etc.

> I plan on implementing this soon for FreeBSD.

May be useful in some cases but won't help nfs numbers....

> 
> rick
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