On 1/9/23 17:03, Jens Axboe wrote:
Because I'm really not thrilled to see the addition of various "is this
device ordered" all over the place, and now we are getting "is this
device ordered AND pipelined". Do you see what I mean? It's making
things _worse_, not better, and we really should be making it better
rather than pile more stuff on top of it.
Hi Jens,
I agree with you that the additional complexity is unfortunate.
For most zoned storage use cases a queue depth above one is not an
option if the zoned device expects zoned write commands in LBA order.
ATA controllers do not support preserving the command order. Transports
like NVMeOF do not support preserving the command order either. UFS is
an exception. The only use case supported by the UFS specification is a
1:1 connection between UFS controller and UFS device with a link with a
low BER between controller and device. UFS controllers must preserve the
command order per command queue. I think this context is well suited for
pipelining zoned write commands.
Thanks,
Bart.
