Re: [PATCH 0/2] Introduce non circular SQ

[Jens Axboe <axboe@kernel.dk>]

On 10/14/25 4:58 AM, Pavel Begunkov wrote:
> Add a feature that makes the kernel to ignore SQ head/tail and
> always start fetching SQ entries from index 0, which helps to
> keep caches hot. See Patch 2 for more details.
> 
> liburing support:
> https://github.com/isilence/liburing.git sq-rewind
> 
> Tested by forcing liburing to enable the flag for compatible setups.
> 
> Pavel Begunkov (2):
>   io_uring: check for user passing 0 nr_submit
>   io_uring: introduce non-circular SQ
> 
>  include/uapi/linux/io_uring.h |  6 ++++++
>  io_uring/io_uring.c           | 34 +++++++++++++++++++++++++---------
>  io_uring/io_uring.h           |  3 ++-
>  3 files changed, 33 insertions(+), 10 deletions(-)

I like the concept of this, makes a lot of sense. No need to keep
churning through the entire SQ ring, when apps mostly submit a few
requests at the time. Will help cut down on cacheline usage.

Curious, do you have any numbers on this for any kind of workload?

-- 
Jens Axboe