[Xenomai] cpu with one core only

Philippe Gerum rpm at xenomai.org
Sun Feb 5 11:58:55 CET 2017

On 02/05/2017 11:55 AM, Ran Shalit wrote:
> On Sat, Feb 4, 2017 at 12:10 PM, Philippe Gerum <rpm at xenomai.org> wrote:
>> On 02/04/2017 09:19 AM, Ran Shalit wrote:
>>> Hello,
>>> It is said in documentation:
>>> "The key issue is with the number of CPU cores actually running
>>> real-time threads and receiving interrupts from real-time sources, not
>>> with the overall number of cores on line on the target hardware.
>>> Because the Cobalt co-kernel does not share any lock with the regular
>>> Linux kernel when dealing with real-time activities, a 16-way server
>>> pinning such activities on not more than four of the available cores
>>> would still deliver good performances in a Cobalt-based dual kernel
>>> configuration."
>>> We plan to use xenomai,
>>> but the cpu (Atom) is only a single core.
>>> Can a single core still gives good results with xenomai ?
>> Yes. There is nothing in the excerpt above which might suggest the
>> opposite btw.
> Hi,
> Do you think it is correct to assume that adding cores will result in
> a (probably) smaller latency ?

No, it is actually the exact opposite. Adding cores will involve more
cache-related latencies, and also require additional serialization for
accessing some critical resources.


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