On 03/05/10 20:14, Kevin Day wrote: > > Recently I bumped into something very weird. In some CPU heavy workloads, > FreeBSD ran faster inside VMware's ESX hypervisor than it did running > natively on bare metal. Simple pure CPU applications (such as "openssl > speed") would run 10-30% faster on VMware. This seemed very counterintuitive, > until I discovered what I believe to be the cause. > > Intel Nehalem and i5/i7 processors have a feature called "Turbo Boost", where > the more cores that are inactive (ACPI states C2 or C3) the higher the clock > rate of the active cores. In some processors increasing the clock speed by > more than 1ghz. On a hunch, I disabled turbo boost (through the BIOS) on our > ESX system, and this brought the speeds back on par with the bare metal > FreeBSD box. > > So, it seems that the VMware hypervisor is deactivating cores on the CPU when > idle, but FreeBSD itself isn't. Is anyone working on giving FreeBSD's idle > loop/scheduler the ability to go into deeper sleep states? It seems this > would have more than just a power savings benefit now. > > Intel documentation on Turbo Boost: > http://download.intel.com/design/processor/applnots/320354.pdf?iid=tech_tb+paper
Howdy Kevin, :) Back in December I started a thread on a related topic because my C2D laptop running -current was running much hotter than usual. Several people were kind enough to offer me suggestions about tuning that I think might be applicable in your situation. I think someone else already gave you the URL http://wiki.freebsd.org/TuningPowerConsumption which was very helpful. Here is what I ended up with after some fiddling with the recommendations from there, and from those kind enough to help me: /boot/loader.conf: hw.pci.do_power_nodriver=3 hint.p4tcc.0.disabled=1 hint.acpi_throttle.0.disabled=1 hint.apic.0.clock=0 kern.hz=100 hint.atrtc.0.clock=0 hint.pcm.0.buffersize=65536 hint.pcm.1.buffersize=65536 hw.snd.feeder_buffersize=65536 hw.snd.latency=7 /etc/rc.conf: powerd_enable="yes" # Run powerd to lower our power usage. powerd_flags="-a adaptive -b adaptive -n adaptive" performance_cpu_freq="NONE" # Online CPU frequency economy_cpu_freq="NONE" # Offline CPU frequency performance_cx_lowest="C3" # Online CPU idle state economy_cx_lowest="C3" # Offline CPU idle state hth, Doug -- ... and that's just a little bit of history repeating. -- Propellerheads Improve the effectiveness of your Internet presence with a domain name makeover! http://SupersetSolutions.com/ _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
