On Wed, Apr 23, 2025 at 07:05:26PM +0200, Holger Hoffstätte wrote: > There may have been a misunderstanding. I first noticed this on an old > machine with SATA SSDs where I *do* have an udev rule for readahead. > I only used my laptop with NVME drive (from ~2021) to reproduce the problem > and send the email. On that machine I do not have any udev rule to set > readahead since it's plenty fast. Ah. > Not sure if that matters, as it was a valid bug after all and now > it's fixed, so thanks again! I usually try to understand what happened to properly document it and create test cases if needed. With your above information I dug a bit deeper and found the likely culprit. Before scsi was converted to the atomic queue limits API, it did not use the proper blk_queue_io_opt API, so it never updated the ra_size based on the optimal I/O. Which means the user value did stick around for SCSI but not the other drivers before.
