https://bugzilla.kernel.org/show_bug.cgi?id=77771 Bug ID: 77771 Summary: Intel P-State: Constantly changing CPU frequencies on idle system. Product: Power Management Version: 2.5 Kernel Version: 3.14.7, 3.15-rc8 - 3.15 Hardware: x86-64 OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: cpufreq Assignee: cpufreq@xxxxxxxxxxxxxxx Reporter: harn-solo@xxxxxx Regression: No With the introduction of the kernel patch 3.14.7 and around the release of 3.15-rc8 the idle CPU frequency of each core in an idle system is changing erratically. Before the patch the output of grep MHz /proc/cpuinfo looked like this: cpu MHz : 813.625 cpu MHz : 813.625 cpu MHz : 813.625 cpu MHz : 813.625 After the patch: cpu MHz : 1600.207 cpu MHz : 1600.207 cpu MHz : 1599.847 cpu MHz : 2342.675 The CPU clocks are wildly changing over the complete spectrum of available frequencies. I can reproduce the phenomenon on at least three systems: Desktop PC with Sandy-Bridge CPU: Intel i7-2600 (non-K) Lenovo T530 with Ivy-Bridge CPU: i7-3610QM Sony VAIO Pro 13 (example above) with Haswell CPU: i5-4200U For me it is not clear whether this is expected behavior and I just hit some kind of heisenbug or something is going wrong. Primarily I report this because I noticed a significant sudden change. I haven't done any tests regarding performance, battery run-time or heat implications yet. Note: I've seen this kind of behavior in earlier kernel releases before, but with 3.14 it vanished completely. So this might be a regression. -- You are receiving this mail because: You are the assignee for the bug. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
