Re: [Ksummit-2005-discuss] Summary of 2005 Kernel Summit Proposed Topics

[Dmitry Yusupov <dmitry_yus@xxxxxxxxx>]

On Sun, 2005-03-27 at 10:26 -0800, Mike Christie wrote:
> Dmitry Yusupov wrote:
> > On Sat, 2005-03-26 at 23:57 -0800, David S. Miller wrote:
> > 
> >>On Sat, 26 Mar 2005 23:05:30 -0800
> >>Dmitry Yusupov <dmitry_yus@xxxxxxxxx> wrote:
> >>
> >>
> >>>>During these gaps in time, you will need to keep your HW receive
> >>>>ring populated with packets.
> >>>
> >>>ethernet flow-control must take care this case.
> >>>
> >>>If driver's replenish logic could mix alloc_skb/netif_rx and SKB
> >>>recycling than pause frames should never happen even with gige+
> >>>interfaces.
> >>
> >>I don't see what the big deal is if pause frames
> >>are generated when the system is low on atomic memory
> >>and RX allocations thus fail.
> > 
> > 
> > not a big deal may be. but. very interesting case when OOM causing
> > paging in/out and swapping device are on the same network under iSCSI
> > control. (disk-less setups) having reliable receive in that case is
> > important for making progress for READ operations.
> 
> reliable receive is ciritical for WRITEs. Even if the WRITE is executed
> successfully on the remote device, if we cannot receive the return status
> from the device the operation will fail at the iscsi driver side due to a
> SCSI timeout.

of course. forget to mention this at the first place. WRITE needs
successful SCSI response too. until that it will not be returned back to
the SCSI Mid-Layer.