Improved Intel Turbo Boost status/control
Alexander Motin <[email protected]>
| Newsgroups | gmane.os.freebsd.current,gmane.os.freebsd.performance |
|---|---|
| Message-ID | <[email protected]> |
Hi. I'd like to note that recent r232793 change to cpufreq(4) in HEAD opened simple access to the Intel Turbo Boost status/control. I've found that at least two of my desktop systems (based Nehalem and SandyBridge Core i7s) with enabled Intel Turbo Boost in BIOS it is not use it by default, unless powerd is enabled. And before this change it was difficult to detect/fix. ACPI reports extra performance level with frequency 1MHz above the nominal to control Intel Turbo Boost operation. It is not a bug, but feature: dev.cpu.0.freq_levels: 2934/106000 2933/95000 2800/82000 ... In this case value 2933 means 2.93GHz, but 2934 means 3.2-3.6GHz. After boot with default settings I see: dev.cpu.0.freq: 2933 , that means Turbo Boost is disabled. Enabling powerd or just adding to rc.conf performance_cpu_freq="HIGH" enables Turbo Boost and adds extra 10-20% to the system performance. Turbo Boost operation can be monitored in run-time via the PMC with command that prints number or really executed cycles per CPU core: pmcstat -s unhalted-core-cycles -w 1 -- Alexander Motin _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "[email protected]"