Re: [PATCH v4] nfsd: allow for up to 32 callback session slots

[Tom Talpey <tom@talpey.com>]

On 11/10/2024 9:24 PM, Olga Kornievskaia wrote:
> On Sat, Nov 9, 2024 at 4:10 PM Jeff Layton <jlayton@kernel.org> wrote:
>> Sounds like a client-side capacity issue? nfs4_callback_recall()
>> returns NFS4ERR_DELAY when nfs_delegation_find_inode() returns -EAGAIN.
>> Maybe there is something weird going on there? Eventually the server
>> has no choice but to revoke an unreturned delegation.
> 
> I'm not trying to imply in any matter that there is a problem with
> either server or client side. I'm simply trying to state that there
> was a theory that having multiple cb_table slots would help in the
> case of having a lot of recalled/revoked state.  What I'm finding is
> that it doesn't seem so (and possibly makes things just slightly
> slower. But no measures were taken so my focus is elsewhere).

We should definitely understand this! I'd say that supporting multiple 
slots is worthwhile and should be merged if stable.

But if they're no better performance-wise, we're missing something. 
There's got to be something else serializing them.

Tom.