On Wed, Nov 13, 2024 at 01:51:48PM -0700, Jens Axboe wrote: > Thanks for testing, but you can't verify any kind of perf change with > that kind of setup. I'll be willing to bet that it'll be 1-2% drop at > higher rates, which is substantial. But the reordering is a problem, not > just for zoned devices, which is why I chose to merge this. So I did not see any variation, but I also don't have access to a really beefy setup right now. If there is a degradation it probably is that touching rq_next for each request actually has an effect if the list is big enough and they aren't cache hot any more. I can cook up a patch that goes back to the scheme currently used upstream in nvme and virtio that just cuts of the list at a hctx change instead of moving the requests one by one now that the block layer doesn't mess up the order.
