> On Oct 7, 2020, at 10:05 AM, Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>
> On Wed, Oct 07, 2020 at 09:45:50AM -0400, Chuck Lever wrote:
>>
>>
>>> On Oct 7, 2020, at 8:55 AM, Benjamin Coddington <bcodding@xxxxxxxxxx> wrote:
>>>
>>> On 7 Oct 2020, at 7:27, Benjamin Coddington wrote:
>>>
>>>> On 6 Oct 2020, at 20:18, J. Bruce Fields wrote:
>>>>
>>>>> On Tue, Oct 06, 2020 at 05:46:11PM -0400, Olga Kornievskaia wrote:
>>>>>> On Tue, Oct 6, 2020 at 3:38 PM Benjamin Coddington <bcodding@xxxxxxxxxx> wrote:
>>>>>>>
>>>>>>> On 6 Oct 2020, at 11:13, J. Bruce Fields wrote:
>>>
>>>>> Looks like nfs4_init_{non}uniform_client_string() stores it in
>>>>> cl_owner_id, and I was thinking that meant cl_owner_id would be used
>>>>> from then on....
>>>>>
>>>>> But actually, I think it may run that again on recovery, yes, so I bet
>>>>> changing the nfs4_unique_id parameter midway like this could cause bugs
>>>>> on recovery.
>>>>
>>>> Ah, that's what I thought as well. Thanks for looking closer Olga!
>>>
>>> Well, no -- it does indeed continue to use the original cl_owner_id. We
>>> only jump through nfs4_init_uniquifier_client_string() if cl_owner_id is
>>> NULL:
>>>
>>> 6087 static int
>>> 6088 nfs4_init_uniform_client_string(struct nfs_client *clp)
>>> 6089 {
>>> 6090 size_t len;
>>> 6091 char *str;
>>> 6092
>>> 6093 if (clp->cl_owner_id != NULL)
>>> 6094 return 0;
>>> 6095
>>> 6096 if (nfs4_client_id_uniquifier[0] != '\0')
>>> 6097 return nfs4_init_uniquifier_client_string(clp);
>>> 6098
>>>
>>>
>>> Testing proves this out as well for both EXCHANGE_ID and SETCLIENTID.
>>>
>>> Is there any precedent for stabilizing module parameters as part of a
>>> supported interface? Maybe this ought to be a mount option, so client can
>>> set a uniquifier per-mount.
>>
>> The protocol is designed as one client-ID per client. FreeBSD is
>> the only client I know of that uses one client-ID per mount, fwiw.
>>
>> You are suggesting each mount point would have its own lease. There
>> would likely be deeper implementation changes needed than just
>> specifying a unique client-ID for each mount point.
>
> Huh, I thought that should do it.
>
> Do you have something specific in mind?
The relationship between nfs_client and nfs_server structs comes to
mind.
Trunking discovery has been around for several years. This is the
first report I've heard of a performance regression.
We do know that nconnect helps relieve head-of-line blocking on TCP.
I think adding a second socket would be a very easy thing to try and
wouldn't have any NFSv4 state recovery ramifications.
--
Chuck Lever
