IO_uring To Ring In Some Awesome Improvements With Linux 6.0

Written by Michael Larabel in Linux Storage on 1 August 2022 at 02:47 PM EDT. 19 Comments
IO_uring continues to be one of the greatest Linux kernel innovations in recent years and with the in-development Linux 6.0 kernel is getting even better along with some nice block updates and other storage-related enhancements.

IO_uring lead developer and block subsystem maintainer Jens Axboe of Meta has submitted his various pull requests of Linux 6.0 changes. With the IO_uring updates for Linux 6.0 there are efficiency improvements to the task-work handling, provided-buffer improvements, improve the cancel hash locking, support for recv/revgmsg multi-shot support for better efficiency with applications doing a lot of receives on an instantiated socket, efficiency improvements for poll handling, and a lot of other clean-ups / improvements.

Jens Axboe at Kernel Recipes 2022.

An additional pull is adding buffered writes support to IO_uring. The IO_uring buffered writes are ready with support for XFS while Btrfs file-system support is in-progress. Axboe explains in that pull:
io_uring does support buffered writes on any file type, but since the buffered write path just always -EAGAIN (or -EOPNOTSUPP) any attempt to do so if IOCB_NOWAIT is set, any buffered write will effectively be handled by io-wq offload. This isn't very efficient, and we even have specific code in io-wq to serialize buffered writes to the same inode to avoid further inefficiencies with thread offload.

This is particularly sad since most buffered writes don't block, they simply copy data to a page and dirty it. With this pull request, we can handle buffered writes a lot more effiently. If balance_dirty_pages() needs to block, we back off on writes as indicated.

This improves buffered write support by 2-3x.

Another pull introduces zero-copy send support for IO_uring. The IO_uring zero-copy send is a big win for networking use-cases. This zero-copy send with IO_uring works for IPv4 and IPv6, both TCP and UDP.

Outside of IO_uring, the block changes have been submitted including various clean-ups, the new user-space block driver using IO_uring, and more.

Lastly are the block driver changes with the NVMe code now seeing support for in-band authentication, improved RAID5 lock contention in the MD code, and various other improvements/fixes/clean-ups.

Meanwhile Jens Axboe is teasing a new AMD EPYC server with 128 cores and 24 Optane drives (Dell PowerEdge R7525) he's been playing with:

With the current Linux kernel he is currently pulliung off 122M IOPS with the 2U server while more than 80% of the system idle. It will be fun to see what further I/O performance optimizations he'll be able to explore with that hardware.
Related News
About The Author
Michael Larabel

Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

Popular News This Week