Date: Tue, 19 Apr 2011 17:43:32 -0500 From: Peter Lai <cowbert@gmail.com> To: freebsd-stable@freebsd.org, freebsd-performance@freebsd.org Subject: t_delta too short while trying to enable C3/TurboBoost Message-ID: <BANLkTikaB5hC_ZxhA2Sg9zh15ZR0xCcQQA@mail.gmail.com>
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Hello I'm trying to enable C3 states to allow TurboBoost on RELENG_8_2 and dmesg is throwing a lot of t_delta too short messages while using boot -v. This platform is 2x Xeon E5620 Gulftown quad core 2.4ghz CPUs on whatever boards Dell ships them on these days (probably Intel X58 derivative.) Kernel is GENERIC for the most part (with network drivers stripped out). Timecounter "i8254" frequency 1193182 Hz quality 0 Calibrating TSC clock ... TSC clock: 2394012372 Hz TSC: P-state invariant ACPI timer: 1/2 1/2 1/1 1/2 1/2 1/1 1/2 1/2 1/2 1/1 -> 10 Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000 acpi_timer0: <24-bit timer at 3.579545MHz> port 0x808-0x80b on acpi0 Here are my loader.conf: hint.p4tcc.0.disabled=1 hint.acpi_throttle.0.disabled=1 kern.hz=100 hint.apic.0.clock=0 hint.atrtc.0.clock=0 rc.conf: 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 and here is sysctl dev.cpu: dev.cpu.0.%desc: ACPI CPU dev.cpu.0.%driver: cpu dev.cpu.0.%location: handle=\_PR_.CPU1 dev.cpu.0.%pnpinfo: _HID=none _UID=0 dev.cpu.0.%parent: acpi0 dev.cpu.0.cx_supported: C1/1 C2/64 C3/96 dev.cpu.0.cx_lowest: C3 dev.cpu.0.cx_usage: 0.90% 0.45% 98.64% last 4096us dev.cpu.1.%desc: ACPI CPU dev.cpu.1.%driver: cpu dev.cpu.1.%location: handle=\_PR_.CPU2 dev.cpu.1.%pnpinfo: _HID=none _UID=0 dev.cpu.1.%parent: acpi0 dev.cpu.1.cx_supported: C1/1 C2/64 C3/96 dev.cpu.1.cx_lowest: C3 dev.cpu.1.cx_usage: 0.68% 0.34% 98.96% last 2965us dev.cpu.2.%desc: ACPI CPU dev.cpu.2.%driver: cpu dev.cpu.2.%location: handle=\_PR_.CPU3 dev.cpu.2.%pnpinfo: _HID=none _UID=0 dev.cpu.2.%parent: acpi0 dev.cpu.2.cx_supported: C1/1 C2/64 C3/96 dev.cpu.2.cx_lowest: C3 dev.cpu.2.cx_usage: 0.94% 0.66% 98.38% last 2081us dev.cpu.3.%desc: ACPI CPU dev.cpu.3.%driver: cpu dev.cpu.3.%location: handle=\_PR_.CPU4 dev.cpu.3.%pnpinfo: _HID=none _UID=0 dev.cpu.3.%parent: acpi0 dev.cpu.3.cx_supported: C1/1 C2/64 C3/96 dev.cpu.3.cx_lowest: C3 dev.cpu.3.cx_usage: 0.81% 0.58% 98.59% last 4124us dev.cpu.4.%desc: ACPI CPU dev.cpu.4.%driver: cpu dev.cpu.4.%location: handle=\_PR_.CPU5 dev.cpu.4.%pnpinfo: _HID=none _UID=0 dev.cpu.4.%parent: acpi0 dev.cpu.4.cx_supported: C1/1 C2/64 C3/96 dev.cpu.4.cx_lowest: C3 dev.cpu.4.cx_usage: 1.07% 0.68% 98.23% last 5046us dev.cpu.5.%desc: ACPI CPU dev.cpu.5.%driver: cpu dev.cpu.5.%location: handle=\_PR_.CPU6 dev.cpu.5.%pnpinfo: _HID=none _UID=0 dev.cpu.5.%parent: acpi0 dev.cpu.5.cx_supported: C1/1 C2/64 C3/96 dev.cpu.5.cx_lowest: C3 dev.cpu.5.cx_usage: 3.01% 1.74% 95.24% last 4504us dev.cpu.6.%desc: ACPI CPU dev.cpu.6.%driver: cpu dev.cpu.6.%location: handle=\_PR_.CPU7 dev.cpu.6.%pnpinfo: _HID=none _UID=0 dev.cpu.6.%parent: acpi0 dev.cpu.6.cx_supported: C1/1 C2/64 C3/96 dev.cpu.6.cx_lowest: C3 dev.cpu.6.cx_usage: 2.45% 1.89% 95.65% last 3506us dev.cpu.7.%desc: ACPI CPU dev.cpu.7.%driver: cpu dev.cpu.7.%location: handle=\_PR_.CPU8 dev.cpu.7.%pnpinfo: _HID=none _UID=0 dev.cpu.7.%parent: acpi0 dev.cpu.7.cx_supported: C1/1 C2/64 C3/96 dev.cpu.7.cx_lowest: C3 dev.cpu.7.cx_usage: 1.21% 0.77% 98.00% last 4180us Should I increment kern.hz until the t_delta too short goes away (I hear that at kern.hz=1000, each core is woken so much by the interrupt counter that it can never enter C3 state) or is there another knob I am supposed to tune? My goal is to see if I can get the box into turboboost as much as possible during idle.
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