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https://git.rwth-aachen.de/acs/public/villas/node/
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61 lines
2 KiB
Markdown
61 lines
2 KiB
Markdown
# Tuning {#tuning}
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This page is not directly related to VILLASnode.
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It describes several ways to optimize the host system for running real-time applications like VILLASnode.
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## Operating System and Kernel
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For minimum latency several kernel and driver settings can be optimized.
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A [PREEMPT_RT patched Linux](https://rt.wiki.kernel.org/index.php/Main_Page) kernel is recommended.
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Precompiled kernels for Fedora can be found here: http://ccrma.stanford.edu/planetccrma/software/
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1. Tune overall system performance for real-time:
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1.1. Use the `tuned` tool for imprving general real-time performance.
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Please adjust the setting `isolated_cpucores` according to your hardware.
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```bash
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$ dnf install tuned-profiles-realtime
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$ echo "realtime" > /etc/tuned/active_profile
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$ echo "isolated_cpucores=6-7" >> /etc/tuned/realtime-variables.conf
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$ systemctl enable tuned && systemctl start tuned
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```
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This enables the following `tuned` profiles:
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- latency-performance
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- network-latency
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- realtime
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1.2 Install a `PREEMPT_RT` patched Linux kernel.
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2. Optimize the VILLASnode configuration
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2.1. Map NIC IRQs (see global setting `affinity`)
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2.2. Map Tasks (see global setting `affinity`)
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2.3. Increase priority of server task (nice(2)) (see global setting `priority`)
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2.4. Increase BSD socket priority (see global setting `priority` for node-type `socket`)
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3. Configure NIC interrupt coalescence with `ethtool`:
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```bash
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$ ethtool --coalesce eth0 adaptive-rx off adaptive-tx off
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```
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4. Configure NIC kernel driver in `/etc/modprobe.d/e1000e.conf`:
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```
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# More conservative interrupt throttling for better latency
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# https://www.kernel.org/doc/Documentation/networking/e1000e.txt
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option e1000e InterruptThrottleRate=
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```
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## Hardware
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This are some proposals for the selection of appropriate server hardware:
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- Server-grade CPU: Intel Xeon
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- A multi-core systems enable true paralell execution of multiple send / receive paths.
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- Server-grade network cards: Intel PRO/1000
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- These allow offloading of UDP checksumming to the hardware
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