>>>>> "Christof" == Christof Schmitt <christof.schmitt@xxxxxxxxxx> writes: Christof> To have a simple approach that covers the case with one Christof> integrity data segment per user data segment, we only report Christof> half the size for the scatterlist length when running Christof> DIX. This guarantees that the other half can be used for Christof> integrity data. Yup, a few of our partners did something similar. My concern is the scenario where we submit lots of 512-byte writes that get merged into (in your case) 4 KB segments. Each of those 512-byte writes could come with an 8-byte integrity metadata tuple. And so you'd need 8 DI scatterlist elements per data element. Christof> Meaning the integrity data sg list would have more entries Christof> than max_segments? I have not seen this during my experiments, Christof> but then i likely have not hit every case of a possible Christof> request layout. dd to the block device is usually a good way to issue long scatterlists. Christof> Ok, i have to look into that as well. It would be an issue Christof> with the approach we are looking at now: If there are Christof> max_segments data segments, and more than max_segments Christof> integrity data segments, we will overrun the hardware Christof> constraint. Ok. -- Martin K. Petersen Oracle Linux Engineering -- 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
