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Improvement on CC errors
Added by Alfred Zastrow about 7 years ago
Hi,
I'm using very low end CPUs for my TVH server and the clients: Asrock N3700 with three PCIE slots for the sat cards from DD and Asrock N3700-ITX for the clients. The CPUs are Intel Pentium N3700 with 4 cores shown in /proc/cpuinfo (it could also be 2 cores with hyperthreading, I'm not sure).
I was facing increasing CC errors when one client was switching channel and I identified some reasons:
1st: During one of the Asrock UEFI-Bios Updates the ACPI-HPET was silent disabled (you can find it in the extended/advanced configuration under ACPI: Enable it
2nd: And this is also (mayby more) important for the KODI-boxes: Deinstall or diable the irqbalancer daemon. This one get's installed (under Debian for example), when in aptitude the switch "install recommended pakets" is set. It is also a good idea to unset this switch.
3rd: it's a good idea too to run this CPUs in performance mode. CPUfreq is a bit oversized, therefore I'm using a simple systemd unit which is started very early after booting.
[Unit] Description=CPU frequency scaling daemon [Service] Type=oneshot RemainAfterExit=no EnvironmentFile=/etc/default/cpufrequtils ExecStart=/bin/sh -c '/bin/echo $governor | /usr/bin/tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor >/dev/null' [Install] WantedBy=sysinit.target
With all these measures the CC errors are almost gone for me. Maybe it could be a help for other users.
br
Alfred
Replies (6)
RE: Improvement on CC errors - Added by Michael Wieland almost 7 years ago
What exactly is "$governor" in your case? I don't have the /etc/default/cpufrequtils file.
RE: Improvement on CC errors - Added by Alfred Zastrow almost 7 years ago
governor="performance"
is the content of my /etc/default/cpufrequtils file
RE: Improvement on CC errors - Added by saen acro almost 7 years ago
With this advice CPU will produce more heat.
In newer kernel's CPU is controlled by P states not by ACPI.
Removing IRQBalance will produce lag in some of real cores of cpu
you can see difference with
watch -d "cat /proc/interrupts"
edit your /etc/modprobe.d/ddbridge.conf
options ddbridge adapter_alloc=3 msi=0and restart
Use powertop
calibrate it run it use optimisations.
RE: Improvement on CC errors - Added by Alfred Zastrow almost 7 years ago
Point me to the "lag" please.
CPU0 CPU1 CPU2 CPU3 0: 16 0 0 0 IO-APIC 2-edge timer 5: 0 0 0 0 IO-APIC 5-edge parport0 8: 0 0 1 0 IO-APIC 8-fasteoi rtc0 9: 0 0 0 0 IO-APIC 9-fasteoi acpi 16: 157643 159155 157750 159162 IO-APIC 16-fasteoi DDBridge 17: 171 174 165 191 IO-APIC 17-fasteoi DDBridge 18: 0 0 0 0 IO-APIC 18-fasteoi i801_smbus 115: 0 0 0 0 PCI-MSI 458752-edge PCIe PME 116: 0 0 0 0 PCI-MSI 460800-edge PCIe PME 117: 0 0 0 0 PCI-MSI 464896-edge PCIe PME 118: 3808 3823 3827 3819 PCI-MSI 311296-edge ahci[0000:00:13.0] 119: 10 9 9 6 PCI-MSI 327680-edge xhci_hcd 120: 148599 147024 148489 147061 PCI-MSI 1572864-edge enp3s0 121: 14271 14307 14259 14256 PCI-MSI 32768-edge i915 122: 144 150 145 150 PCI-MSI 442368-edge snd_hda_intel:card0 NMI: 90 21 19 19 Non-maskable interrupts LOC: 12719085 11453043 12149559 11913869 Local timer interrupts SPU: 0 0 0 0 Spurious interrupts PMI: 90 21 19 19 Performance monitoring interrupts IWI: 3 0 0 0 IRQ work interrupts RTR: 0 0 0 0 APIC ICR read retries RES: 7164 5006 7572 6704 Rescheduling interrupts CAL: 2580 2525 4129 3126 Function call interrupts TLB: 76 72 56 41 TLB shootdowns TRM: 0 0 0 0 Thermal event interrupts THR: 0 0 0 0 Threshold APIC interrupts DFR: 0 0 0 0 Deferred Error APIC interrupts MCE: 0 0 0 0 Machine check exceptions MCP: 241 241 241 241 Machine check polls ERR: 1
btw.: regarding ACPI: The "High Precision Event Timer (HPET)" feature is listed within the ACPI-Options of the Asrock BIOS.
btw2: "more heat" needs more power consumtion, I can't measure it.
RE: Improvement on CC errors - Added by saen acro almost 7 years ago
your lan card how traffic pass?
https://www.phoronix.com/scan.php?page=article&item=intel_pstate_linux315&num=1
after kernel 4.4 ACPI is not used as before.
you can use lm-sensors
RE: Improvement on CC errors - Added by Alfred Zastrow almost 7 years ago
Sorry, but I stop this discussion now.