On 11/13/24 11:33 AM, Bart Van Assche wrote: > > On 11/13/24 7:20 AM, Christoph Hellwig wrote: >> currently blk-mq reorders requests when adding them to the plug because >> the request list can't do efficient tail appends. When the plug is >> directly issued using ->queue_rqs that means reordered requests are >> passed to the driver, which can lead to very bad I/O patterns when >> not corrected, especially on rotational devices (e.g. NVMe HDD) or >> when using zone append. >> >> This series first adds two easily backportable workarounds to reverse >> the reording in the virtio_blk and nvme-pci ->queue_rq implementations >> similar to what the non-queue_rqs path does, and then adds a rq_list >> type that allows for efficient tail insertions and uses that to fix >> the reordering for real and then does the same for I/O completions as >> well. > > Hi Christoph, > > Could something like the patch below replace this patch series? I > don't have a strong opinion about which approach to select. I mean it obviously could, but it'd be a terrible way to go as we're now iterating the full list just to reverse it... -- Jens Axboe
