Another Linux 4.20 Performance Regression Has Now Been Addressed (THP)
Written by Michael Larabel in Linux Kernel on 6 December 2018 at 06:39 AM EST. Add A Comment
LINUX KERNEL --
The bumpy Linux 4.19~4.20 road continues but at least another performance regression is now crossed off.

Google's David Rientjes has landed a patch in mainline Linux 4.20 Git as of yesterday that restores node-locale hugepage allocations. Changes to Transparent Huge-Pages, which THP itself was designed to improve performance and make it easier to utilize huge-pages, had caused a performance regression to be introduced back during the 4.20 merge window.

In terms of the 4.20 performance regression, "On Haswell, [one of the problematic commits] was shown to have a 13.9% access regression after this commit for binaries that remap their text segment to be backed by transparent hugepages... If remote memory is also low or fragmented, not setting __GFP_THISNODE was also measured on Haswell to have a 40% regression in allocation latency."

More details on the changes to Transparent Huge-Pages via this kernel commit.

About The Author
Author picture

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 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 OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

Related Linux Kernel News
Popular News This Week