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Beide Seiten der vorigen RevisionVorhergehende ÜberarbeitungNächste Überarbeitung | Vorhergehende Überarbeitung | ||
software:linux:realtime:benchmark:start [2019-02-08 16:37] – mgehrig2 | software:linux:realtime:benchmark:start [2023-04-11 11:17] (aktuell) – gelöscht Urs Graf | ||
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- | ====== Benchmark ======= | ||
- | ===== Introduction ===== | ||
- | There are many different tools available to measure the realtime performance of a system. | ||
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- | The cyclictest is the simplest and most usefull benchmark. | ||
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- | ===== Tools ===== | ||
- | ==== Cyclictest ==== | ||
- | Standard tool to measure the maximum jitter of a system. | ||
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- | **[[software: | ||
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- | ===== Influences on real-time behaviour ===== | ||
- | The following things can influence the real-time behaviour: | ||
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- | * CPU | ||
- | * Mobile x86 CPU (with suffix like U, Y and M i.e i7-4600U) seems to perform much worse than non-mobile processors. Mobile processer add about 100us-200us jitter. | ||
- | * ARM processer seem to have about 60us max jitter and a high medium jitter | ||
- | * Kernel version | ||
- | * 4.4.169-rt177 seems to be better than 4.19.15-rt12 | ||
- | * BIOS settings | ||
- | * Some drivers, like WiFi driver, may negatively influence latency | ||
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- | ===== Methodical procedure ===== | ||
- | ==== Overview ==== | ||
- | At first, test the most basic system possible. | ||
- | With this test, you can get a baseline of the best possible real-time performance of the hardware. | ||
- | Every feature added will make the system more complex and add more stuff, which can increase jitter. | ||
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- | With this approach you can get a feeling which performance is possible and which part of the system is responsible for a high jitter. | ||
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- | - Test hardware, BIOS settings and kernel version | ||
- | - Test full distro in text mode | ||
- | - Test full distro in graphical mode | ||
- | - Test full distro under load | ||
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- | ==== Test hardware, BIOS settings and kernel version ==== | ||
- | - Build a [[software: | ||
- | - Install the [[software: | ||
- | - Reboot with the new kernel in [[software: | ||
- | - Check the real-time performance with [[software: | ||
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- | === Tuning === | ||
- | If you the measured latencies are to high, you can tweak your system. | ||
- | The options which are simple but effective are listed first. | ||
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- | * Tune some [[software: | ||
- | * Tune some kernel settings TODO | ||
- | * Use a different kernel version. (4.4.169-rt177 seems to be better than 4.19.15-rt12) | ||
- | * If the jitter is still to high, you may have to choose a different CPU | ||
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