Linux 4.16 Getting Tweak For Smarter Task Migration, Yielding Better Scalability
Written by Michael Larabel in Linux Kernel on 29 January 2018 at 06:45 AM EST. 5 Comments
LINUX KERNEL --
Ingo Molnar began sending in his various Git pull requests this morning for targeting the Linux 4.16 kernel merge window, including the scheduler updates.

One of the kernel scheduler changes catching our attention was Mel Gorman's sched/fair: Only immediately migrate tasks due to interrupts if prev and target CPUs share cache.

The change now only considers an automatic migration of tasks resulting from interrupts if the previous and anticipated CPU cores share the same cache. With the current kernel behavior depending upon the system's topology and IRQ settings, all of the work could be punted off to the same node.

With this NUMA migration change on a two-socket system, Gorman found a small increase in throughput performance while the standard deviation in Dbench I/O runs benefited as well. The change reduced CPU migrations by about 24% with this one line of code changed.

The scheduler changes can be found via this pull request while the particular patch of interest can be found here.
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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 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.

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