linux-kernel - [PATCH V2] arch_topology: support parsing cluster

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Date:   Thu, 12 May 2022 11:21:23 +0000
From:   王擎 <wangqing@...o.com>
To:     Dietmar Eggemann <dietmar.eggemann@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH V2] arch_topology: support parsing cluster_id from DT


>[...]
>
>> @@ -582,7 +594,8 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
>>                        }
>>  
>>                        if (leaf) {
>> -                             ret = parse_core(c, package_id, core_id++);
>> +                             ret = parse_core(c, package_id, (depth == 2)?cluster_id : -1,
>> +                                            core_id++);
>>                        } else {
>>                                pr_err("%pOF: Non-leaf cluster with core %s\n",
>>                                       cluster, name);
>> @@ -599,9 +612,6 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
>>        if (leaf && !has_cores)
>>                pr_warn("%pOF: empty cluster\n", cluster);
>>  
>> -     if (leaf)
>> -             package_id++;
>> -
>>        return 0;
>>  }
>
>The issue I mentioned under
>https://lkml.kernel.org/r/bd746cf0-0fdd-1ee6-d394-67fffb5d9b58@arm.com
>still exists.

Yes, I get it, will be fixed in V3.

>
>Btw, I recommend the following test strategy.
>
>(A) Create a set of dts files which represent today's topologies in DT:
>
>  (1) 8 CPUs flat (Arm DynamIQ single DSU)
>
>  (2) 2 groups of 4 CPUs (e.g. hikey 960) (which covers Phantom* domain)
>
>  (3) your QC SM8450 Armv9 tri-gear (4-3-1) DynamIQ single DSU w/ shared
>      L2 btwn CPU0-1 and CPU2-3.
>  ...
>
> * used in Android
>
>(B) Compile dtb's
>
>  dtc -I dts -O dtb -o foo.dtb foo.dts
>
>
>(C) Run them under qemu w/ and w/o CONFIG_SCHED_CLUSTER and check:
>
>  sudo qemu-system-aarch64 ... -dtb foo.dtb
>
>  (1) sched domains:
>
>      cat /sys/kernel/debug/sched/domains/cpu*/domain*/name
>
>  (2) sched flags:
>
>      cat /sys/kernel/debug/sched/domains/cpu*/domain*/flags
>
>  (3) cpumasks:
>
>      cat /proc/schedstat | awk '{print $1 " " $2 }' | grep ^[cd]
>
>You can even mention the test results in your patch so that people see
>that you already covered them. This will speed up the review-process
>enormously.

Yes, because I'm not sure if this idea is correct. I will add it in the
next version, thank you again.

Qing