RE: [[PATCH v1] 25/37] [CIFS] SMBD: Support SMBD idle connection timer

[Long Li]

> -----Original Message-----
> From: Tom Talpey
> Sent: Monday, August 14, 2017 2:12 PM
> To: Long Li <longli@xxxxxxxxxxxxx>; Steve French <sfrench@xxxxxxxxx>;
> linux-cifs@xxxxxxxxxxxxxxx; samba-technical@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Cc: Long Li <longli@xxxxxxxxxxxxx>
> Subject: RE: [[PATCH v1] 25/37] [CIFS] SMBD: Support SMBD idle connection
> timer
> 
> > -----Original Message-----
> > From: linux-cifs-owner@xxxxxxxxxxxxxxx [mailto:linux-cifs-
> > owner@xxxxxxxxxxxxxxx] On Behalf Of Long Li
> > Sent: Wednesday, August 2, 2017 4:11 PM
> > To: Steve French <sfrench@xxxxxxxxx>; linux-cifs@xxxxxxxxxxxxxxx;
> > samba- technical@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > Cc: Long Li <longli@xxxxxxxxxxxxx>
> > Subject: [[PATCH v1] 25/37] [CIFS] SMBD: Support SMBD idle connection
> > timer
> >
> > +static int keep_alive_interval = 120;
> 
> This is the recommended value, but not the only possibility.
> 
> > @@ -1348,6 +1369,10 @@ struct cifs_rdma_info*
> cifs_create_rdma_session(
> >         init_waitqueue_head(&info->wait_send_queue);
> >         init_waitqueue_head(&info->wait_reassembly_queue);
> >
> > +       INIT_DELAYED_WORK(&info->idle_timer_work,
> idle_connection_timer);
> > +       schedule_delayed_work(&info->idle_timer_work,
> > +               info->keep_alive_interval*HZ);
> > +
> 
> This initialization is ok, but the timer should be rescheduled (extended) any
> time any packet is sent. There is no need to perform keepalives on an active
> SMB Direct connection.

My feeling is that rescheduling on a work queue for every packet is sent is not efficient, especially under heavy conditions.

Firing it every 120 seconds doesn't seem to be big waste and may actually save some CPU.

> 
> Tom.