Hello
Since Linux 4.6 (and still in 4.9-rc5 at least), both AMD Bulldozer
cores of a single dual-core compute unit report the same core_id:
$ cat /sys/devices/system/cpu/cpu{?,??}/topology/core_id
0
0
1
1
2
2
3
0
3
[...]
Before 4.5 (and for a very long time), the kernel reported different
core_ids:
0
1
2
3
4
5
6
7
0
[...]
This causes user-space tools (at least all that rely on hwloc for
topology discovery) to think the processor has dual-threaded cores
instead of dual-core compute-unit modules.
The cause is likely this patch, which seems to assume both cores of a
same compute-unit have the same ID, which is wrong?
commit 8196dab4fc159943df6baaac04973bb1accb7100
Author: Borislav Petkov <b...@suse.de>
Date: Fri Mar 25 15:52:36 2016 +0100
x86/cpu: Get rid of compute_unit_id
It is cpu_core_id anyway.
Signed-off-by: Borislav Petkov <b...@suse.de>
Link: http://lkml.kernel.org/r/1458917557-8757-3-git-send-email...@alien8.de
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Thanks
Brice
