Hacker News Reader

Dear folks, I'm the author of that post.

A short summary below.

We ran fio benchmarks comparing libaio and io_uring across kernels (5.4 -> 7.0-rc3). The most surprising part wasn’t io_uring gains (~2x), but a ~30% regression caused by IOMMU being enabled by default between releases.

Happy to share more details about setup or reproduce results.

View on HN

Thanks for sharing this.

Was the iommu using strict or lazy invalidation? I think lazy is the default but I'm not sure how long that's been true.

We compared IOMMU fully disabled vs enabled. When it is enabled, I expect it to be lazy (should be the default for IOMMU). Note, that we recommend to use passthrough to completely bypass translation for most devices independent on strict/lazy mode.

Reply on news.ycombinator.com