libpfc | small library and kernel module

by obilaniu C Version: Current License: MIT

X-Ray Key Features Code Snippets Community Discussions(1)Vulnerabilities Install Support

kandi X-RAY | libpfc Summary

libpfc is a C library. libpfc has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can download it from GitLab, GitHub.

A small library and kernel module for easy access to x86 performance monitor counters under Linux.

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libpfc has a low active ecosystem.

It has 61 star(s) with 9 fork(s). There are 9 watchers for this library.

It had no major release in the last 6 months.

There are 7 open issues and 11 have been closed. On average issues are closed in 17 days. There are no pull requests.

It has a neutral sentiment in the developer community.

The latest version of libpfc is current.

Quality

libpfc has 0 bugs and 0 code smells.

Security

libpfc has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

libpfc code analysis shows 0 unresolved vulnerabilities.

There are 0 security hotspots that need review.

License

libpfc is licensed under the MIT License. This license is Permissive.

Permissive licenses have the least restrictions, and you can use them in most projects.

Reuse

libpfc releases are not available. You will need to build from source code and install.

Installation instructions are not available. Examples and code snippets are available.

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libpfc Key Features

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libpfc Examples and Code Snippets

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Community Discussions

Trending Discussions on libpfc

Lost Cycles on Intel? An inconsistency between rdtsc and CPU_CLK_UNHALTED.REF_TSC

QUESTION

Lost Cycles on Intel? An inconsistency between rdtsc and CPU_CLK_UNHALTED.REF_TSC

Asked 2018-Apr-20 at 02:12

On recent CPUs (at least the last decade or so) Intel has offered three fixed-function hardware performance counters, in addition to various configurable performance counters. The three fixed counters are:

...

ANSWER

Answered 2017-Aug-09 at 14:37

TL;DR

The discrepancy you are observing between RDTSC and REFTSC and is due to TurboBoost P-state transitions. During these transitions, most of the core, including the fixed-function performance counter REF_TSC, is halted for approximately 20000-21000 cycles (8.5us), but rdtsc continues at its invariant frequency. rdtsc is probably in an isolated power and clock domain because it is so important and because of its documented wallclock-like behaviour.

The RDTSC-REFTSC Discrepancy

The discrepancy manifests itself as a tendency for RDTSC to overcount REFTSC. The longer the program runs, the more positive the difference RDTSC-REFTSC tends to be. Over very long stretches it can mount as high as 1%-2% or even higher.

Of course, it has been observed by yourself already that the overcounting disappears when TurboBoost is disabled, which can be done as follows when using intel_pstate:

Source https://stackoverflow.com/questions/45472147

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install libpfc

You can download it from GitLab, GitHub.

Support

For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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