On Sep 12, 2012, at 3:20 AM, Hartmut Behrens <hartmut.behrens@xxxxxxxxx> wrote: > Hi, > > I have patched a 3.2 kernel for a OMAP compatible processor (ARM > Cortex A8) to be used on an Gumstix Overo with the CONFIG_PREEMPT_RT > patch. > > I have noticed that the latency of the patched kernel on this platform > is <300usec (using cyclictest), similar to what is reported for the > ARM9 platforms at > https://rt.wiki.kernel.org/index.php/CONFIG_PREEMPT_RT_Patch > > Is this the best performance that can be expected from ARM7/9 platforms? > > Could it be improved by using different kernel config settings - e.g. > CONFIG_LATENCY_TRACE=n - > https://rt.wiki.kernel.org/index.php/Cyclictest mentions that latency > tracing adds significant kernel overhead? There are a lot of options that can be eliminated / optimized to reduce memory footprint and overhead. If you are not using large scale SMP features, things like cgroups, name spaces and so on may shave a few nanoseconds here and there, and that adds up. You'll have to experiment with the configs, but for typical embedded, less is more. Historically, if you can run a UP configured Kernel, that tends to be much more lightweight. The OSADL configs Carsten referenced in separate email are certainly a good starting point. If you find compile errors as you twiddle with options, please do send the relevant snippets to this list. Thanks Sven > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
