On 2023/3/28 09:16, Ming Lei wrote:
Hi Dan,
On Mon, Mar 27, 2023 at 05:36:33PM -0700, Dan Williams wrote:
Ming Lei wrote:
Hello Jens,
Add IORING_OP_FUSED_CMD, it is one special URING_CMD, which has to
be SQE128. The 1st SQE(master) is one 64byte URING_CMD, and the 2nd
64byte SQE(slave) is another normal 64byte OP. For any OP which needs
to support slave OP, io_issue_defs[op].fused_slave needs to be set as 1,
and its ->issue() can retrieve/import buffer from master request's
fused_cmd_kbuf. The slave OP is actually submitted from kernel, part of
this idea is from Xiaoguang's ublk ebpf patchset, but this patchset
submits slave OP just like normal OP issued from userspace, that said,
SQE order is kept, and batching handling is done too.
Hi Ming,
io_uring and ublk are starting to be more on my radar these days. I
wanted to take a look at this series, but could not get past the
distracting "master"/"slave" terminology in this lead-in paragraph let
alone start looking at patches.
Frankly, the description sounds more like "head"/"tail", or even
"fuse0"/"fuse1" because, for example, who is to say you might not have
The term "master/slave" is from patches.
The master command not only provides buffer for slave request, but also requires
slave request for serving master command, and master command is always completed
after all slave request are done.
That is why it is named as master/slave. Actually Jens raised the similar concern
and I hate the name too, but it is always hard to figure out perfect name, or
any other name for reflecting the relation? (head/tail, fuse0/1 can't
do that, IMO)
larger fused ops in the future and need terminology to address
"fuse{0,1,2,3}"?
Yeah, definitely, the interface can be extended in future to support
multiple "slave" requests.
I guess master/slave (especially now) have bad meaning to
English-language guys so it's better to avoid it.
Thanks,
Gao Xiang
Thanks,
Ming
