On 10-11-18 04:50 PM, James Bottomley wrote:
Before we go gung ho on this, there's no evidence that N discontiguous ranges in one command are any better than the ranges sent N times ... the same amount of erase overhead gets sent on SSDs.
No, we do have evidence: execution time of the TRIM commands on the SSD. The one-range-at-a-time is incredibly slow compared to multiple ranges at a time. That slowness comes from somewhere, with about 99.9% certainty that it is due to the drive performing slow flash erase cycles. I think perhaps we should do the batching as much as possible, and then split them into single ranges for LLDs that cannot handle multi-ranges. Way more efficient that way. Cheers -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
