[Lustre-devel] extend lnet_notify to public LNet API

[Nic Henke <nic@cray.com>]

On 11/16/2010 10:00 AM, Nic Henke wrote:
> We'd like to allow upper layers (Lustre, Cray DVS, etc) to register a
> callback that would be called from lnet_notify. This will allow them to
> be notified when the lower layers have seen network problems between
> NIDs and let them take appropriate action. The upper layer could also be
> notified when that peer has returned to 'network health' after the LND
> gets its act together.
>
> This would help allow upper layers to aggressively resend/reconnect in
> the cases where all TX have completed successfully (meaning no LNet -EIO
> on LND errors) but there are LNET_MSG_ACK or other REPLY traffic
> outstanding.
>
> Initial proposal is on the verbose side, giving all data that
> lnet_notify sees:
> - lnet_nid_t
> - is_alive (boolean)
> - cfs_time_t when (unsigned long on Linux) - jiffies when last alive
>

One oddity - if the LND has peer_health disabled (no ni_peertimeout 
value), there doesn't seem to be anything that'd set the peer back to 
'up'. Am I missing something or is this as desired ?

Nic