Re: [patch] scsi: use lock per host instead of per device for shared queue tag host

Jeff Garzik
2007-01-26T01:21:12Z

Ed Lin wrote:
> There may possibly be some other errors. So we need a lock here.
> I think the simple but reliable way to do it is just to replace
> queue lock with a host lock. James pointed out that there may be
> performance slow down when many devices are accessed at the
> same time. But I think the major part is still on the hardware,
> and a host lock is the price these kind of controllers must pay.

I agree.

Further, a host lock is (a) common across many controllers, to protect
host-wide resources and (b) only limits us when the controller is
CPU-limited, a very rare scenario.

Jeff