Jeff Garzik wrote: > The other reason why we use one-short-per-port on master/slave is that, > in many respects, each legacy IDE port really can behave like a > completely separate controller, each port with its own interrupts and > independent reset logic. > > Thus ATA really has two models: 1-port-1-host and N-ports-1-host. One thing that having a per-port SCSI host buys us is that it isolates EH to the port rather than the entire SCSI host. The way that the new libata EH is designed, it can end up spending a fair amount of time in EH and may even sleep for seconds at a time, waiting for the device to come ready. Quiescing all devices on a SAS host due to a single SATA device gets *very* painful. The new libata EH does much more than just EH. It wakes up for every ATAPI check condition... Before we can move to a single SCSI host model, we will have to make some changes regarding how EH is done in libata... -Brian -- Brian King Linux on Power Virtualization IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
