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Torvalds advocates daily kernel performance tests

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Published: 30 Mar 2005 17:00 BST

Linux founder Linus Torvalds on Tuesday called for more regular performance tests on the Linux kernel so that any reduction in efficiency can be highlighted sooner.

Currently performance figures are only available for a few of the latest production kernels. Torvalds said it would be useful to continually test the performance of the development kernel, so that inefficient code can be spotted more easily.

"Doing just release kernels means that there will be a two-month lag between telling developers that something pissed up performance," said Torvalds in a posting to the Linux kernel mailing list. "Doing it every day (or at least a couple of times a week) will be much more interesting."

The issue was raised when Intel employee Kenneth Chen announced some performance figures for various versions of the 2.6 kernel. The tests found that versions 2.6.11, 2.6.9, 2.6.8 and 2.6.2 of the kernel performed 13, 6, 23 and 1 percent slower respectively than the Red Hat Enterprise Linux 3 baseline — which runs on version 2.4 of the kernel, with some added features from version 2.6.

Torvalds said that more granular results are needed to be able to work out what code caused the significant changes in performance between the different versions.

"For example, that 2.6.2 -> 2.6.8 change obviously makes pretty much any developer just go 'I've got no clue'," said Torvalds. "It would be interesting (still) to go back in time if the benchmark can be done fast enough, and try to do testing of the historical weekly (if not daily) builds to see where the big differences happened."

Chen said that he will try to persuade his management to do more regular performance tests. "I sure will make my management know that Linus wants to see the performance number on a daily basis," said Chen.