From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Darren Hart <darren@os.amperecomputing.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Will Deacon <will@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux Arm <linux-arm-kernel@lists.infradead.org>,
Sudeep Holla <sudeep.holla@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Barry Song <song.bao.hua@hisilicon.com>,
Valentin Schneider <Valentin.Schneider@arm.com>,
"D . Scott Phillips" <scott@os.amperecomputing.com>,
Ilkka Koskinen <ilkka@os.amperecomputing.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v3] topology: make core_mask include at least cluster_siblings
Date: Mon, 14 Mar 2022 10:37:21 +0100 [thread overview]
Message-ID: <35344252-5284-b08e-fec7-6dc99476b4b0@arm.com> (raw)
In-Reply-To: <YijxUAuufpBKLtwy@fedora>
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.
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next prev parent reply other threads:[~2022-03-14 9:39 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-04 17:01 [PATCH v3] topology: make core_mask include at least cluster_siblings Darren Hart
2022-03-08 10:30 ` Will Deacon
2022-03-08 10:45 ` Sudeep Holla
2022-03-08 11:04 ` Vincent Guittot
2022-03-08 16:03 ` Dietmar Eggemann
2022-03-08 17:49 ` Darren Hart
2022-03-09 12:50 ` Dietmar Eggemann
2022-03-09 18:26 ` Darren Hart
2022-03-14 9:37 ` Dietmar Eggemann [this message]
2022-03-14 16:56 ` Darren Hart
2022-03-16 14:42 ` Dietmar Eggemann
2022-03-14 16:35 ` Dietmar Eggemann
2022-03-14 16:54 ` Darren Hart
2022-03-16 14:48 ` Dietmar Eggemann
2022-03-16 15:20 ` Darren Hart
2022-03-16 15:55 ` Sudeep Holla
2022-03-21 14:30 ` Will Deacon
2022-03-21 15:56 ` Greg Kroah-Hartman
2022-03-14 21:29 ` [PATCH] arch_topology: Swap MC & CLS SD mask if MC weight==1 & kernel test robot
2022-03-14 23:02 ` kernel test robot
2022-03-17 6:10 ` [PATCH v3] topology: make core_mask include at least cluster_siblings Barry Song
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