RHEL-RT RealtimeSystemTuningHowto

From RHEL-RT

Contents 1 Realtime System Tuning 1.1 Try these first 1.2 Consider these later 1.3 Realtime Performance Monitoring Tools 2 Future content

Realtime System Tuning

This section describes realtime specific tuning. These knobs are not available on standard RHEL5. Before performing realtime specific tuning, it is assumed that you have previously performed and measured the benefits of General system tuning - RHEL-RT GeneralSystemTuningHowto.

Try these first

This section highlights the realtime specific tuning which is likely to have the most effect in achieving consistent determinism.

• Setting Realtime Scheduler Priorities - tuning the priorities of kernel threads and realtime priority applications: RHEL-RT SchedPrioHowto

Consider these later

• gettimeofday(2) speedup - RHEL-RT VDSOHowto

• Realtime BIOS firmware settings - some BIOS features can randomly introduce non-determinism. Model specific BIOS parameters may be required.: RHEL-RT BiosParametersHowto

• Enabling kexec/kdump with the realtime kernel - Setting up for kdump and kexec is fairly simple. Instructions are here: RHEL-RT kdump/kexec

• Enabling TSC timer synchronization on Opteron CPUs - To ensure timer synchronization in multiprocessor AMD Opteron based systems, it is recommended to enable the TSC timer synchronization mechanism. Instructions are here: RHEL-RT AMDTSCsyncEnableHowto

• Infiniband - Notes on infiniband support in RHEL-RT: RHEL-RT Infiniband

Realtime Performance Monitoring Tools

• Latency Tracer - how to utilize the latency tracer to identify sources of kernel non-determinism and understand its output: RHEL-RT LatencyTracerHowto

• User-triggered Latency Tracing - how to use trace-cmd to measure latencies during the runtime of a given application: RHEL-RT TraceCmdHowto

Future content

This section highlights additional topics we intend to cover, which are related to realtime system tuning:

• Advice on configuring and using (or disabling) the following system services: power management, cpufreq, cpuspeed, irqbalance
• How to do least intrusive profiling of lock contention
• Advice on setting application realtime priorities