Infoportal
Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
| 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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