Fix pqos startup vs. clock stepping race condition - Githubissues

intel / intel-cmt-cat

User space software for Intel(R) Resource Director Technology

http://www.intel.com/content/www/us/en/architecture-and-technology/resource-director-technology.html

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Fix pqos startup vs. clock stepping race condition #201

Closed gsauthof closed 2 years ago

gsauthof commented 2 years ago

This change fixes #194 by replacing the custom nanosleep time computation with a timerfd file descriptor.

Description

See https://github.com/intel/intel-cmt-cat/issues/194#issuecomment-978161482 for a detailed analysis.

Affected parts

[ ] library
[x] pqos utility
[ ] rdtset utility
[ ] other: (please specify)

Motivation and Context

Previously, I noticed pqos consuming 100% and calling syscalls at an ultra high rate, when started as part of a systemd service, during boot.

Obviously, such an issue is a show stopper for serious usage.

How Has This Been Tested?

Tested it in the environment where I previously could reproduce the issue very reliably.

Types of changes

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

[x] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.

gsauthof commented 2 years ago

PS: As a drive-by fix I also removed the stripping of the executables. Looks like this is better left to the packaging folks. (e.g. rpm strips binaries, by default)

NB: Although the executables were stripped, the shared object wasn't.