https://bugzilla.kernel.org/show_bug.cgi?id=49231 Summary: Single CPU bound process results in non-optimal turbo boost configuration Product: Power Management Version: 2.5 Kernel Version: 3.4.4+ Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: cpufreq AssignedTo: cpufreq@xxxxxxxxxxxxxxx ReportedBy: ras243-korg@xxxxxxxxx Regression: No Created an attachment (id=84251) --> (https://bugzilla.kernel.org/attachment.cgi?id=84251) 3.4.13 config file Firstly I hope I've classified this issue correctly as it's a bit difficult to nail down exactly what's at fault. I have a new i7-3930k CPU on an Intel DX79SR motherboard which doesn't appear to be handling the turbo boost function correctly under Linux. This is a 6 core CPU which is nominally 3.2GHz but can boost itself to somewhere between 3.5GHz and 3.8GHz. With 6 processes running it'll run at 3.5GHz which is fine. The problem is that when only a single process is active it'll still only run at 3.5GHz despite being able to go to 3.8GHz. The problem appears to be that a single job is pulling all the cores out of C7 state and into at least C1 state and once there, they're all are considered active and hence the fully utilised CPU is unable to go beyond 3.5GHz. I am unsure if the problem is with the scheduler, ACPI, or something in my configuration. I can confirm that a 3.4.4 kernel configuration which works correctly on a Xeon X5660 doesn't work correctly with the i7-3930k. I've tried various kernels between 3.4.4 and 3.6.2 but all result in the same behaviour. With gritted teeth I installed Windows 7 and it does appear to work correctly there so I don't believe it's anything to do with BIOS settings. Idle turbostat results: core CPU %c0 GHz TSC %c1 %c3 %c6 %c7 %pc2 %pc3 %pc6 %pc7 2.73 1.20 3.20 7.06 0.00 0.02 90.19 20.20 0.00 68.20 0.00 0 0 2.68 1.20 3.20 6.92 0.00 0.00 90.40 20.20 0.00 68.20 0.00 1 1 2.75 1.20 3.20 6.92 0.00 0.00 90.33 20.20 0.00 68.20 0.00 2 2 2.78 1.20 3.20 6.99 0.00 0.00 90.23 20.20 0.00 68.20 0.00 3 3 2.71 1.20 3.20 7.10 0.00 0.00 90.19 20.20 0.00 68.20 0.00 4 4 2.71 1.20 3.20 7.14 0.00 0.07 90.07 20.20 0.00 68.20 0.00 5 5 2.76 1.20 3.20 7.27 0.00 0.07 89.90 20.20 0.00 68.20 0.00 Single job turbostat results: core CPU %c0 GHz TSC %c1 %c3 %c6 %c7 %pc2 %pc3 %pc6 %pc7 18.46 3.50 3.20 81.54 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0 2.02 3.50 3.20 97.98 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1 1 2.19 3.50 3.20 97.81 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 2 2.20 3.50 3.20 97.80 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3 3 2.17 3.50 3.20 97.83 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4 4 100.00 3.50 3.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 5 2.18 3.50 3.20 97.82 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- 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
