On 02/04/2013 08:07 AM, dbasehore . wrote:
On the topic that we do a fast return for both scsi and ata. Now I don't remember everything about this (and correct me if I'm wrong) since I figured this out a few months ago. There are some dependencies that scsi has on the resume path of ata. I think it's that before we can send the command to spin up the disk, we need to wait for the ata host controller to come up. As Aaron Lu pointed out, it takes seconds for the ata port to resume. On the hand,
I just did some more recording, the result is: host controller takes 1ms or less to resume; port reset takes the most time, almost the same as the whole port resume callback, 2-4 seconds; sd resume callback takes 16ms. So for ata disks, the most time consuming part is in port's reset routine, which is executed in port's resume callback. -Aaron -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
