On 09/03/2022 19:26, Darren Hart wrote:
On Wed, Mar 09, 2022 at 01:50:07PM +0100, Dietmar Eggemann wrote:
On 08/03/2022 18:49, Darren Hart wrote:
On Tue, Mar 08, 2022 at 05:03:07PM +0100, Dietmar Eggemann wrote:
On 08/03/2022 12:04, Vincent Guittot wrote:
On Tue, 8 Mar 2022 at 11:30, Will Deacon will@kernel.org wrote:
[...]
IMHO, if core_mask weight is 1, MC will be removed/degenerated anyway.
This is what I get on my Ampere Altra (I guess I don't have the ACPI changes which would let to a CLS sched domain):
# cat /sys/kernel/debug/sched/domains/cpu0/domain*/name DIE NUMA root@oss-altra01:~# zcat /proc/config.gz | grep SCHED_CLUSTER CONFIG_SCHED_CLUSTER=y
I'd like to follow up on this. Would you share your dmidecode BIOS Information section?
# dmidecode -t 0 # dmidecode 3.2 Getting SMBIOS data from sysfs. SMBIOS 3.2.0 present.
Handle 0x0000, DMI type 0, 26 bytes BIOS Information Vendor: Ampere(TM) Version: 0.9.20200724 Release Date: 2020/07/24 ROM Size: 7680 kB Characteristics: PCI is supported BIOS is upgradeable Boot from CD is supported Selectable boot is supported ACPI is supported UEFI is supported BIOS Revision: 5.15 Firmware Revision: 0.6
Thank you, I'm following internally and will get with you.
Looks like in my PPTT, the `Processor Hierarchy Nodes` which represents cluster nodes have no valid `ACPI Processor ID`.
Example for CPU0:
cpu_node-:
[1B9Ch 7068 1] Subtable Type : 00 [Processor Hierarchy Node] [1B9Dh 7069 1] Length : 1C [1B9Eh 7070 2] Reserved : 0000 [1BA0h 7072 4] Flags (decoded below) : 0000001A Physical package : 0 ACPI Processor ID valid : 1 <-- valid !!! Processor is a thread : 0 Node is a leaf : 1 Identical Implementation : 1 [1BA4h 7076 4] Parent : 00001B88 <-- parent !!! [1BA8h 7080 4] ACPI Processor ID : 00001200 [1BACh 7084 4] Private Resource Number : 00000002 [1BB0h 7088 4] Private Resource : 00001B58 [1BB4h 7092 4] Private Resource : 00001B70
cluster_node (cpu_node->parent):
[1B88h 7048 1] Subtable Type : 00 [Processor Hierarchy Node] [1B89h 7049 1] Length : 14 [1B8Ah 7050 2] Reserved : 0000 [1B8Ch 7052 4] Flags (decoded below) : 00000010 Physical package : 0 ACPI Processor ID valid : 0 <-- not valid !!! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Processor is a thread : 0 Node is a leaf : 0 Identical Implementation : 1 [1B90h 7056 4] Parent : 000001C8 [1B94h 7060 4] ACPI Processor ID : 00000000 [1B98h 7064 4] Private Resource Number : 00000000
The code which checks this is:
int find_acpi_cpu_topology_cluster(unsigned int cpu) { .... if (cluster_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID) retval = cluster_node->acpi_processor_id; else retval = ACPI_PTR_DIFF(cluster_node, table);
The else patch just returns distinct values for each CPU, so there is no sub-grouping of CPUs which can lead to a CLS SD.