>>>>> "Jeff" == Jeff Garzik <jeff@xxxxxxxxxx> writes: Jeff> In an ideal world where information and engineers are cost-free... Oh, yeah... Jeff> if a device is non-rotational, we should know this, whether it's Jeff> ancient compact flash, or gigabyte's DRAM-based ATA device, or Jeff> modern SSD. It shouldn't be a question of whether or not treating Jeff> a non-rotational device as a non-rotational device is performance Jeff> win -- because if you're asking that question, it might imply Jeff> areas where we are making invalid assumptions about certain Jeff> classes of non-rotational devices :) Well, there were a few attempts at getting SSD performance metrics into ATA. They failed for political/marketing reasons. Even if we had gotten the metrics we wanted I'm sure most vendors would have indicated that "this one goes to eleven". All we have is non-rotational which means "seeks are cheaper than on rotating media". And for a lot of older/slower flash devices it's actually a win to do merging because command latency can be quite high. So it's not necessarily a win to go non-rotational. Which is why I suggested looking at numbers instead of blindly whitelisting every ATA flash device known to man. However, now it appears that what Greg really needs is a supports_secure_erase flag... -- Martin K. Petersen Oracle Linux Engineering -- 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
