On 2024/12/17 11:58, Jens Axboe wrote: > On 12/17/24 12:54 PM, Jens Axboe wrote: >> io_uring does support ordering writes - not because of zoning, but to >> avoid buffered writes being spread over a bunch of threads and hence >> just hammering the inode mutex rather than doing actual useful work. You >> could potentially use that. Then all pending writes for that inode would >> be ordered, even if punted to io-wq. > > See io_uring/io_uring.c:io_prep_async_work(), which is called when an IO > is added for io-wq execution, io_wq_hash_work() makes sure it'll be > ordered. However, this will still not work if you're driving beyond the > limit of the device queue depth, or if you're doing IOs that may trigger > -EAGAIN spuriously for -EAGAIN as you can still have two issuers - the > task itself submitting IO, and the one io-wq worker tasked with doing > blocking writes on this zoned device. Thanks for the pointer. Will have a look. It may be as simple as always using the io-wq worker for zone writes and have these ordered (__WQ_ORDERED). Maybe. -- Damien Le Moal Western Digital Research
