On Thu, Jan 02, 2025 at 10:49:41AM +0100, Niklas Cassel wrote: > > > from below information, it seems an 'ahci' to me. but since I have limited > > > knowledge about storage driver, maybe I'm wrong. if you want more information, > > > please let us know. thanks a lot! > > > > Yes, this looks like ahci. Thanks a lot! > > Did this ever get resolved? > > I haven't seen a patch that seems to address this. > > AHCI (ata_scsi_queuecmd()) only issues a single command, so if there is any > reordering when issuing a batch of commands, my guess is that the problem > also affects SCSI / the problem is in upper layers above AHCI, i.e. SCSI lib > or block layer. I started looking into this before the holidays. blktrace shows perfectly sequential writes without any reordering using ahci, directly on the block device or using xfs and btrfs when using dd. I also started looking into what the test does and got as far as checking out the stress-ng source tree and looking at stress-aiol.c. AFAICS the default submission does simple reads and writes using increasing offsets. So if the test result isn't a fluke either the aio code does some weird reordering or btrfs does. Oliver, did the test also show any interesting results on non-btrfs setups?
