SMP for Embedded linux

zvivered · 08-05-2009, 02:18 PM

We want to run a vanilla version on a Core2Duo x86 CPU.
Our application is one process with many threads. We want to
tell linux on which CPU to run a specified thread. The reason is determinism.

If we let Linux decide this it can lead to an undeterministic system. This is OK in desktop applications, not in my embedded system.

Is "manual" SMP in linux a mature capability ? Is it wise to use it on
a "soft" real time system ?

Thanks.

vermaden · 08-05-2009, 02:28 PM

We have used it on routers/servers without any problems.

jf.argentino · 08-06-2009, 06:22 AM

You can assign a thread to on CPU only with:

Code:

   cpu_set_t cpuset;
   CPU_ZERO (&cpuset);
   CPU_SET (cpu_id, &cpuset);
   sched_setaffinity (syscall (SYS_gettid), sizeof (cpu_set_t), &cpuset);

Where "cpu_id" is between 0 and the nb of cpu you have less 1.
_BUT_ assigning a thread to a given CPU doesn't mean that any other process can run on this CPU, thus it won't be more deterministic. If you really need determinism you have to use something like xenomai...