Re: [PATCH 2/6] scsi: avoid taking host_lock in scsi_run_queue unless nessecary

[Christoph Hellwig <hch@infradead.org>]

On Wed, Feb 12, 2014 at 12:08:35PM +0100, Hannes Reinecke wrote:
> What happens when another CPU is just modifying the starved list
> at this point?
> We probably won't be seeing the update until when the next command
> completed.

That's correct if the last was emptry previous.  list_empty won't
return true when adding an additional command.

> Which probably doesn't matter if the HBA has run out of resources
> (which means there are plenty of other commands outstanding),
> but it'll surely influence the load balancing when using several
> devices, won't it?

Only when first adding an item to the starved list.  Load balancing
isn't that important when just dealing with two commands but more
for a long lasting overload.