>>>>> "Frank" == Frank Mayhar <fmay...@google.com> writes:
Frank, Frank> Well, in this particular case the driver is filling in the Frank> relevant information (alignment and granularity) and then Frank> complaining later that that information has been ignored. As I Frank> intimated earlier, it seems a little odd to allow the driver to Frank> specify the information, only to ignore it completely when it's Frank> time to actually use it. Which driver is this? In T10 SBC these values are performance hints, not hard requirements. They were never intended as such. Frank> Further, in my opinion this is less "dropping information" than Frank> it is keeping information that would be dropped by the driver Frank> itself; were it not for this adjustment, the driver would get the Frank> request, complain, and drop it completely. This way, as much of Frank> the request as possible is preserved while still honoring the Frank> constraints given by the driver. The problem arises if you combine devices with different granularity. The I/O topology code is then forced to scale the granularity up. If you enforce the granularity at the top of the stack it means the device(s) with lesser granularity will lose information which would otherwise be valuable to them. We have previously entertained enforcing the granularity at the bottom of the stack on a per-device basis. However, I stand by my opinion that the device behavior is broken. I'd never let a device like that pass qualification here... -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
