Setting physical CPU for a task

[Adam Lackorzynski]

On Mon Aug 05, 2013 at 21:50:55 +0300, Lluís Vilanova wrote:
> I've been unable to see if moe's config files allow to start tasks pinned to a
> specific CPU, and after running the "thread_migrate" example, looks like only
> one CPU (CPU00) is always used:
> 
>   $ make -C obj/l4/amd64/ qemu E=thread_migrate QEMU_OPTIONS="-serial stdio -vnc ::59000 -smp 2"
>   [...]
>   Not using serial hack in slow timer handler.
>   CPU[0]: AuthenticAMD (6:2:3:0)[00000623] Model: QEMU Virtual CPU version 1.5.1 at 3092MHz
> 
>    255/512 Entry I TLB (4K pages)    255 Entry I TLB (4M pages)
>    255/512 Entry D TLB (4K pages)    255 Entry D TLB (4M pages)
>     64 KB L1 I Cache (2-way associative, 64 bytes per line)
>     64 KB L1 D Cache (2-way associative, 64 bytes per line)
>    512 KB L2 U Cache (8-way associative, 64 bytes per line)
> 
>   Freeing init code/data: 20480 bytes (5 pages)
>   [...]
>   Ned says: Hi World!
>   Ned: loading file: 'rom/thread_migrate.cfg'
>   migrate | Found 4 CPUs.
>   migrate | Created 12 threads.
>   migrate | Migrated Thread00 -> CPU00
>   migrate | Migrated Thread01 -> CPU00
> 
> I've modified "src/l4/conf/modules.list" to add the "thread_migrate" test, and
> I'm using l4re-snapshot-2013060718, with multiprocessing (with a maximum of 4)
> enabled on fiasco.
> 
> Looks like the benchmark always detects (L4::Scheduler::info) the number of
> maximum CPUs configured in fiasco, but not the number of CPUs provided by QEMU
> (only CPU 0 is online).

That it finds 4 is on purpose because more CPUs could come up.
Does it work giving Qemu '-cpu core2duo'?

> Am I missing some step to set all CPUs online? Is it possible to have MOE start
> tasks pinned to a specific CPU?

See the (commented out) "scheduler = ... " settings in, e.g., x86-fb.cfg
and give a fourth parameter, which is a CPU mask. You can check in the
kernel debugger on which CPU a thread is (via lp command).



Adam
-- 
Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/