Re: FlexSC influence on io_uring

[Jens Axboe <axboe@kernel.dk>]

On 1/31/22 11:55 AM, Spencer Baugh wrote:
> 
> Hi,
> 
> To what extent, if any, was the FlexSC paper an influence on io_uring?
> 
> FlexSC is described in a paper from 2010:
> https://www.usenix.org/legacy/events/osdi10/tech/full_papers/Soares.pdf
> 
> FlexSC is a system for asynchronous system calls aimed at achieving
> high-performance by avoiding the cost of system calls, in particular the
> locality costs of executing kernel code and user code on the same core.
> 
> Implementation-wise, it seems broadly similar to io_uring, in that
> system calls are submitted by writing to some location in memory, which
> is later picked up by a syscall-execution thread (ala
> IORING_SETUP_SQPOLL) which executes it and writes back the result.
> 
> I'm just curious if there was any influence from FlexSC on io_uring.

Wasn't aware of this paper, if that answers the question. The idea for
async syscalls (to me) date back to the original threadlet/acall ideas
from Zach Brown and Ingo, though my implementation ended up being vastly
different. The API with the rings of shared memory was a pretty obvious
one and not really novel, it's been used in both sw and hw for a long
time.

-- 
Jens Axboe