[Deepin-Kernel-SIG] [linux 6.6-y] [Deepin] sched/fair: Disable newidle balance for KABI #1456
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Reviewer's guide (collapsed on small PRs)Reviewer's GuideThis PR conditionally disables the proportional newidle balancing feature and its associated statistics when Deepin KABI reservation is enabled, to keep sched_domain’s layout stable for KABI while preserving existing behavior otherwise. Class diagram for sched_domain layout under CONFIG_DEEPIN_KABI_RESERVEclassDiagram
class SchedulerConfig {
<<config>>
+bool CONFIG_DEEPIN_KABI_RESERVE
}
class sched_domain_non_kabi {
+unsigned int nr_balance_failed
+unsigned int newidle_call
+unsigned int newidle_success
+unsigned int newidle_ratio
+u64 max_newidle_lb_cost
+unsigned long last_decay_max_lb_cost
}
class sched_domain_kabi_reserve {
+unsigned int nr_balance_failed
+u64 max_newidle_lb_cost
+unsigned long last_decay_max_lb_cost
}
SchedulerConfig --> sched_domain_non_kabi : CONFIG_DEEPIN_KABI_RESERVE = false
SchedulerConfig --> sched_domain_kabi_reserve : CONFIG_DEEPIN_KABI_RESERVE = true
Flow diagram for newidle balancing behavior with CONFIG_DEEPIN_KABI_RESERVEflowchart TD
A["CPU becomes newly idle"] --> B{CONFIG_DEEPIN_KABI_RESERVE}
B -- false --> C["update_newidle_stats increments newidle_call and newidle_success"]
C --> D{sched_feat NI_RANDOM}
D -- true --> E["Apply randomized weighting for newidle balancing"]
D -- false --> F["Use default weight for newidle balancing"]
E --> G["Call load_balance with CPU_NEWLY_IDLE"]
F --> G["Call load_balance with CPU_NEWLY_IDLE"]
B -- true --> H["Skip newidle_call/newidle_success/newidle_ratio updates"]
H --> I["NI_RANDOM feature disabled at compile time"]
I --> J["Call load_balance with CPU_NEWLY_IDLE using default behavior"]
File-Level Changes
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deepin inclusion category: kabi some kabi whitelist symbol changed, such as set_cpus_allowed_ptr..etc. the symbol chain is: int wake_up_process(struct task_struct *tsk);->struct task_struct ->struct sched_dl_entity dl,*dl_server; ->struct rq *rq; ->struct sched_domain __rcu *sd; -> +unsigned int newidle_call; +unsigned int newidle_success; +unsigned int newidle_ratio; Before find the way to solve it, disable it for CONFIG_DEEPIN_KABI_RESERVE. Log: change set_cpus_allowed_ptr change wake_up_process change set_user_nice Fixes: 97d5537 ("sched/fair: Proportional newidle balance") Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
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Pull request overview
This PR disables proportional newidle balancing to preserve kernel ABI stability for Deepin by guarding struct members and features with CONFIG_DEEPIN_KABI_RESERVE. The changes prevent ABI breakage in exported symbols like wake_up_process and set_cpus_allowed_ptr by conditionally removing three new fields (newidle_call, newidle_success, newidle_ratio) from struct sched_domain that were added by commit 97d5537.
Changes:
- Conditionally removes three newidle statistics fields from struct sched_domain
- Guards the NI_RANDOM scheduler feature flag to disable proportional balancing
- Protects all code paths that use the removed fields and feature
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| include/linux/sched/topology.h | Adds deepin_kabi.h include and guards newidle statistics fields in struct sched_domain with CONFIG_DEEPIN_KABI_RESERVE |
| kernel/sched/topology.c | Conditionally excludes initialization of newidle statistics fields in sd_init() |
| kernel/sched/features.h | Guards the NI_RANDOM feature flag definition |
| kernel/sched/fair.c | Guards update_newidle_stats() implementation and NI_RANDOM-based proportional balancing logic |
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This way of fixing is kind of gross... |
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deepin inclusion
category: kabi
some kabi whitelist symbol changed, such as set_cpus_allowed_ptr..etc. the symbol chain is:
int wake_up_process(struct task_struct *tsk);->struct task_struct ->struct sched_dl_entity dl,*dl_server;
->struct rq *rq;
->struct sched_domain __rcu *sd;
->
+unsigned int newidle_call;
+unsigned int newidle_success;
+unsigned int newidle_ratio;
Before find the way to solve it, disable it for CONFIG_DEEPIN_KABI_RESERVE.
Log:
change set_cpus_allowed_ptr
change wake_up_process
change set_user_nice
Fixes: 97d5537 ("sched/fair: Proportional newidle balance")
Summary by Sourcery
Disable proportional newidle balancing when Deepin KABI reservation is enabled to preserve kernel ABI stability.
Enhancements:
Summary by Sourcery
Guard proportional newidle balancing and its statistics behind Deepin KABI reservation to avoid changing the sched_domain ABI layout.
Enhancements: