Date: Mon, 12 Mar 2012 21:55:21 +0200 From: Alexander Motin <mav@FreeBSD.org> To: Ivan Klymenko <fidaj@ukr.net> Cc: freebsd-performance@FreeBSD.org, FreeBSD current <freebsd-current@freebsd.org> Subject: Re: Improved Intel Turbo Boost status/control Message-ID: <4F5E54A9.5050301@FreeBSD.org> In-Reply-To: <4f5e4f82.41972a0a.0e49.2cfdSMTPIN_ADDED@mx.google.com> References: <4F5E4B57.1050605@FreeBSD.org> <4f5e4f82.41972a0a.0e49.2cfdSMTPIN_ADDED@mx.google.com>
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On 03/12/12 21:33, Ivan Klymenko wrote: > В Mon, 12 Mar 2012 21:15:35 +0200 > Alexander Motin<mav@FreeBSD.org> пишет: >> 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 >> > > Thank you very much! > performance_cpu_freq="HIGH" > and as this option must be combined with state of the processor C1 C2 > C3? > performance_cx_lowest="XX" > economy_cx_lowest="XX" The more CPU cores on package are sleeping and the deeper they are sleeping, the bigger will be boost for remaining active cores. Without using deeper C-states boost is usually quite small (about 100-200MHz for desktop chips). Enabling C-states increases it in few times. -- Alexander Motin
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