Xen With Linux 5.16 Will Allow For Faster Booting Of Guests

Written by Michael Larabel in Virtualization on 9 November 2021 at 01:50 PM EST. 15 Comments
Xen para-virtualized guests booting on the Linux 5.16 kernel should see noticeably quicker boot times.

Sent out today were the Xen patches for Linux 5.16. Besides having some code clean-ups, para-virtualized interrupt masking made simpler, Xen "pciback" driver support for Arm, and other smaller enhancements, there is also work to speed-up guest booting. In particular, the booting up of Xen PV (para-virtualized) guests should be much quicker with Linux 5.16 and beyond.

Jan Beulich of SUSE wrote in the prior patch series when first proposing the Xen PV guest boot optimizations, "The observed (by the human eye) performance difference of early boot between native and PV-on-Xen was just too large to not look into. As it turns out, gaining performance back wasn't all that difficult. While the series (re)introduces a small number of PTWR emulations on the boot path (from phys_pte_init()), there has been a much larger number of them post-boot. Hence I think if this was of concern, the post-boot instances would want eliminating first."

More details via the Xen pull request for the Linux 5.16 kernel merge window that is ending this weekend.
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Michael Larabel is the principal author of Phoronix.com 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 OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.

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