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Date: Wed, 11 May 2022 09:38:54 +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] arch_topology: support parsing cluster_id from DT
>> From: Wang Qing <wangqing@...o.com>
>>
>> Use nested cluster structures in DT to support describing multi-level
>> cluster topologies.
>>
>> Notice: the clusters describing in DT currently are not physical
>> boundaries, since changing "cluster" to "socket" is too involved and error
>> prone, this patch will not have any effect on one-level cluster topo, but
>> can support the mutil-level cluster topo to support CLUSTER_SCHED.
>>
>> Signed-off-by: Wang Qing <wangqing@...o.com>
>> ---
>> drivers/base/arch_topology.c | 25 +++++++++++++++++--------
>> 1 file changed, 17 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
>> index 1d6636ebaac5..f2ea8113d619 100644
>> --- a/drivers/base/arch_topology.c
>> +++ b/drivers/base/arch_topology.c
>> @@ -491,7 +491,7 @@ static int __init get_cpu_for_node(struct device_node *node)
>> }
>>
>> static int __init parse_core(struct device_node *core, int package_id,
>> - int core_id)
>> + int cluster_id, int core_id)
>> {
>> char name[20];
>> bool leaf = true;
>> @@ -507,6 +507,7 @@ static int __init parse_core(struct device_node *core, int package_id,
>> cpu = get_cpu_for_node(t);
>> if (cpu >= 0) {
>> cpu_topology[cpu].package_id = package_id;
>> + cpu_topology[cpu].cluster_id = cluster_id;
>> cpu_topology[cpu].core_id = core_id;
>> cpu_topology[cpu].thread_id = i;
>> } else if (cpu != -ENODEV) {
>> @@ -528,6 +529,7 @@ static int __init parse_core(struct device_node *core, int package_id,
>> }
>>
>> cpu_topology[cpu].package_id = package_id;
>> + cpu_topology[cpu].cluster_id = cluster_id;
>> cpu_topology[cpu].core_id = core_id;
>> } else if (leaf && cpu != -ENODEV) {
>> pr_err("%pOF: Can't get CPU for leaf core\n", core);
>> @@ -544,13 +546,15 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
>> bool has_cores = false;
>> struct device_node *c;
>> static int package_id __initdata;
>> + static int cluster_id __initdata;
>
>Starting with cluster_id = 0 breaks existing platforms like
>./arch/arm64/boot/dts/arm/juno.dts. For them it has to be still set to -1.
Yes, I noticed this problem, please help to review version V2.
>
>You get e.g.:
>
># cat /sys/kernel/debug/sched/domains/cpu1/domain*/name
>CLS
>DIE
>
>instead of:
>
># cat /sys/kernel/debug/sched/domains/cpu1/domain*/name
>MC
>DIE
>
>
>> int core_id = 0;
>> int i, ret;
>>
>> /*
>> - * First check for child clusters; we currently ignore any
>> - * information about the nesting of clusters and present the
>> - * scheduler with a flat list of them.
>> + * nesting of clusters :
>> + * level 1: package_id
>> + * level 2: cluster_id
>> + * level 3+: ignore
>> */
>> i = 0;
>> do {
>> @@ -559,6 +563,14 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
>> if (c) {
>> leaf = false;
>> ret = parse_cluster(c, depth + 1);
>> + if (depth == 0) {
>> + package_id++;
>> + cluster_id = 0;
>
>- cluster_id = 0;
>+ cluster_id = -1;
This modification is not enough..
>
>Would have to be cluster_id = -1. 0 is a valid 2. level cluster.
>Otherwise you're not removing the CLS data from CPU4 to CPU7 in the
>`Armv9 with L2 complexes` cpu-map example I used for testing:
>
> cpu-map {
> cluster0 {
> cluster0 {
> core0 {
> cpu = <&cpu0>;
> };
> core1 {
> cpu = <&cpu1>;
> };
> };
> cluster1 {
> core0 {
> cpu = <&cpu2>;
> };
> core1 {
> cpu = <&cpu3>;
> };
> };
> };
> cluster1 {
> core0 {
> cpu = <&cpu4>;
> };
> core1 {
> cpu = <&cpu5>;
> };
> core2 {
> cpu = <&cpu6>;
> };
> };
> cluster2 {
> core0 {
> cpu = <&cpu7>;
> };
> };
> };
>
>> + } else if (depth == 1)
>> + cluster_id++;
>> + else
>> + pr_err("Ignore nested clusters with more than two levels!\n");
>> +
>> of_node_put(c);
>> if (ret != 0)
>> return ret;
>> @@ -582,7 +594,7 @@ 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, cluster_id, core_id++);
>> } else {
>> pr_err("%pOF: Non-leaf cluster with core %s\n",
>> cluster, name);
>> @@ -599,9 +611,6 @@ 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;
>> }
>
>Looks like you also need to adapt update_siblings_masks() to only set
>cpu in &cpu_topo->thread_sibling and &cpuid_topo->thread_sibling when
>`cpu_topo->thread_id != -1`.
>
>@@ -723,11 +723,11 @@ void update_siblings_masks(unsigned int cpuid)
> cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
> cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
>
>- if (cpuid_topo->core_id != cpu_topo->core_id)
>- continue;
>-
>- cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
>- cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
>+ if (cpu_topo->thread_id != -1 &&
>+ cpuid_topo->core_id == cpu_topo->core_id) {
>+ cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
>+ cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
>+
This seems like another problem?
Thanks,
Qing
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