Linux Kernel To Get AIO Performance Improvements
Written by Michael Larabel in Linux Kernel on 4 December 2012 at 02:36 AM EST. 16 Comments
The Linux Kernel A-synchronous I/O support has been receiving some performance improvements and clean-ups that should soon be merged to mainline.

Coming out recently have been a set of more than two dozen patches for the Linux AIO support that provides notable performance improvements. From the patch-set's author on the AIO mailing list, "The results in my testing are pretty impressive, particularly when an ioctx is being shared between multiple threads. In my crappy synthetic benchmark, with 4 threads submitting and one thread reaping completions, I saw overhead in the aio code go from ~50% (mostly ioctx lock contention) to low single digits. Performance with ioctx per thread improved too, but I'd have to rerun those benchmarks. The reason I've been focused on performance when the ioctx is shared is that for a fair number of real world completions, userspace needs the completions aggregated somehow - in practice people just end up implementing this aggregation in userspace today, but if it's done right we can do it much more efficiently in the kernel."

Yesterday there was a second version of these kernel AIO patches for enhancing the performance. It's possible we will see the a-synchronous I/O performance improvements merged into the Linux 3.8 kernel later this month if further revisions aren't deemed necessary that would stave off the merging to Linux 3.9. The AIO changes affect around one thousand lines of kernel code.

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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 10,000 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 or contacted via

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