[PATCH OLK-5.10 v8 0/4] arm64: Allow CPU0 to be nohz_full
Changelog: v1->v2: change __setup() to early_param() v2->v3: fix kabi because #include <linux/sched/isolation.h> modify defconfig v3->v4: fix riscv compile error: move support_cpu0_nohz_full to tick.h v4->v5: fix kabi change v5->v6: Only check whether there exists only one online housekeeping CPU v6->v7: modify comments and commit message v7->v8: change BUG_ON(1) to BUG() Xiongfeng Wang (4): isolation: Do not check whether housekeeping CPUs are present isolation: Check whether there exists a housekeeping CPU online arm64: Kconfig: select ARCH_SUSPEND_NONZERO_CPU by default arm64: defconfig: Enable CONFIG_ARCH_SUSPEND_NONZERO_CPU and CONFIG_ARCH_SUSPEND_NONZERO_CPU arch/arm64/Kconfig | 3 +++ arch/arm64/configs/openeuler_defconfig | 2 ++ include/linux/cpu.h | 5 +++- include/linux/sched/isolation.h | 2 ++ include/linux/tick.h | 2 ++ kernel/sched/isolation.c | 33 ++++++++++++++++++++++---- kernel/smp.c | 4 ++++ kernel/time/tick-sched.c | 11 ++++++++- 8 files changed, 56 insertions(+), 6 deletions(-) -- 2.30.0
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hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9NR7Q CVE: NA -------------------------------- If we set isolcpus without CPU0, it will print the following error: [ 0.000000] Housekeeping: must include one present CPU, using boot CPU:0 It is because when string 'isolcpus=xxx' is parsed, only CPU0 is set as present for arch arm64. Unlike X86 and PowerPC, the present_cpu_mask is set rather late in smp_prepare_cpus() for arm64. In CPU hotplug situation, some possible CPUs are not marked as present, only CPUs with its GICC marked as ACPI_MADT_ENABLED are marked as present. So we cannot set preset_cpu_mask for all possible CPUs at early stage. Only check cpu_present_mask cannot assure that the CPUs will be broughtup online, as described in the below Link1. So do not check whether housekeeping CPUs are present when parsing 'isolcpus'. A following commit will add check after CPU online process is finished, as suggested in below Link2. Link1: https://lore.kernel.org/all/20190504002733.GB19076@lenoir/ Link2: https://lore.kernel.org/all/1557186148.ocs72ssdjc.astroid@bobo.none/ Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> --- include/linux/tick.h | 2 ++ kernel/sched/isolation.c | 20 ++++++++++++++++---- kernel/time/tick-sched.c | 9 +++++++++ 3 files changed, 27 insertions(+), 4 deletions(-) diff --git a/include/linux/tick.h b/include/linux/tick.h index f34b7b779d44..46c75dccaf8e 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -41,8 +41,10 @@ extern void tick_irq_enter(void); # ifndef arch_needs_cpu # define arch_needs_cpu() (0) # endif +extern bool support_cpu0_nohz_full; # else static inline void tick_irq_enter(void) { } +#define support_cpu0_nohz_full 0 #endif #if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_TICK_ONESHOT) diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 785ef5201116..68cd58539e40 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -96,18 +96,30 @@ static int __init housekeeping_setup(char *str, enum hk_flags flags) alloc_bootmem_cpumask_var(&housekeeping_mask); cpumask_andnot(housekeeping_mask, cpu_possible_mask, non_housekeeping_mask); + if (support_cpu0_nohz_full && cpumask_empty(housekeeping_mask)) { + pr_warn("Housekeeping cpumask is NULL, using boot CPU\n"); + __cpumask_set_cpu(smp_processor_id(), housekeeping_mask); + /* + * update non_housekeeping_mask because it will be used below + * in tick_nohz_full_setup(). + */ + cpumask_andnot(non_housekeeping_mask, + cpu_possible_mask, housekeeping_mask); + } cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask); - if (cpumask_empty(tmp)) { + if (!support_cpu0_nohz_full && cpumask_empty(tmp)) { pr_warn("Housekeeping: must include one present CPU, " "using boot CPU:%d\n", smp_processor_id()); __cpumask_set_cpu(smp_processor_id(), housekeeping_mask); __cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask); } } else { - cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask); - if (cpumask_empty(tmp)) - __cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask); + if (!support_cpu0_nohz_full) { + cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask); + if (cpumask_empty(tmp)) + __cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask); + } cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask); if (!cpumask_equal(tmp, housekeeping_mask)) { pr_warn("Housekeeping: nohz_full= must match isolcpus=\n"); diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f50dc8f36707..d7bc1358af79 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -38,6 +38,8 @@ */ static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched); +bool support_cpu0_nohz_full; + struct tick_sched *tick_get_tick_sched(int cpu) { return &per_cpu(tick_cpu_sched, cpu); @@ -1559,3 +1561,10 @@ int tick_check_oneshot_change(int allow_nohz) tick_nohz_switch_to_nohz(); return 0; } + +static int __init support_cpu0_nohz_full_setup(char *str) +{ + support_cpu0_nohz_full = true; + return 0; +} +early_param("support_cpu0_nohz_full", support_cpu0_nohz_full_setup); -- 2.30.0
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9NR7Q CVE: NA -------------------------------- We need to make sure that the housekeeper, one of the housekeeping CPUs, is online, as describe in the below Link. We add this check after secondary CPUs online is finished. Link: https://lore.kernel.org/all/20190504002733.GB19076@lenoir/ Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> --- include/linux/sched/isolation.h | 2 ++ kernel/sched/isolation.c | 13 +++++++++++++ kernel/smp.c | 4 ++++ 3 files changed, 19 insertions(+) diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h index 2f93081ad7a0..f665bc8ff633 100644 --- a/include/linux/sched/isolation.h +++ b/include/linux/sched/isolation.h @@ -26,6 +26,7 @@ extern bool housekeeping_enabled(enum hk_flags flags); extern void housekeeping_affine(struct task_struct *t, enum hk_flags flags); extern bool housekeeping_test_cpu(int cpu, enum hk_flags flags); extern void __init housekeeping_init(void); +extern void check_housekeeping_cpu_online(void); #else @@ -48,6 +49,7 @@ static inline bool housekeeping_enabled(enum hk_flags flags) static inline void housekeeping_affine(struct task_struct *t, enum hk_flags flags) { } static inline void housekeeping_init(void) { } +static inline void check_housekeeping_cpu_online(void) { } #endif /* CONFIG_CPU_ISOLATION */ static inline bool housekeeping_cpu(int cpu, enum hk_flags flags) diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 68cd58539e40..237b24bbbcc4 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -218,3 +218,16 @@ static int __init enhanced_isolcpus_setup(char *str) return 0; } __setup("enhanced_isolcpus", enhanced_isolcpus_setup); + +void check_housekeeping_cpu_online(void) +{ + if (!support_cpu0_nohz_full) + return; + if (!housekeeping_flags) + return; + if (!cpumask_intersects(housekeeping_mask, cpu_online_mask)) { + pr_err("All the housekeeping CPUs are offline, please modify the kernel parameter !\n"); + /* BUG() here, otherwise we may BUG() in sched_init_smp(). */ + BUG(); + } +} diff --git a/kernel/smp.c b/kernel/smp.c index 4b13a7ef6a31..d9ba6935f83f 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -20,6 +20,7 @@ #include <linux/cpu.h> #include <linux/sched.h> #include <linux/sched/idle.h> +#include <linux/sched/isolation.h> #include <linux/hypervisor.h> #include <linux/sched/clock.h> #include <linux/nmi.h> @@ -884,6 +885,9 @@ void __init smp_init(void) /* Any cleanup work */ smp_cpus_done(setup_max_cpus); + + /* Check whether there exists a housekeeping CPU online */ + check_housekeeping_cpu_online(); } /* -- 2.30.0
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9NR7Q CVE: NA -------------------------------- Commit 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full") allow CPU0 to be housekeeping CPU. But it is only supproted when CONFIG_PM_SLEEP_SMP is not configured, or when it is configured and the arch allows suspend on non-zero CPUs. We cannot disable CONFIG_PM_SLEEP_SMP because freeze_secondary_cpus(), which is used in kexec, is included in the config. For arm64, there is not restriction in kernel to prevent nonzero cpu entering suspend using PSCI interface. when ARCH_SUSPEND_NONZERO_CPU is enabled, PM_SLEEP_SMP_NONZERO_CPU will be also enabled. The only influence is that suspend_disable_secondary_cpus() will use a housekeeping CPU to enter suspend. If pm sleep/hibernate is not involved, only kexec will use this function, which is tested on a arm64 server, and the vmcore can be created successfully. We add 'enable_cpu0_nohz_full' in the CONFIG_PM_SLEEP_SMP_NONZERO_CPU check branch. When 'enable_cpu0_nohz_full' is zero. There is no functional change. Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> --- arch/arm64/Kconfig | 3 +++ include/linux/cpu.h | 5 ++++- kernel/time/tick-sched.c | 2 +- 3 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 273a58b74470..eb7334370cfe 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2306,6 +2306,9 @@ config ARCH_HIBERNATION_HEADER config ARCH_SUSPEND_POSSIBLE def_bool y +config ARCH_SUSPEND_NONZERO_CPU + def_bool y + endmenu menu "CPU Power Management" diff --git a/include/linux/cpu.h b/include/linux/cpu.h index c282f6355aef..623e764cab13 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -18,6 +18,9 @@ #include <linux/compiler.h> #include <linux/cpumask.h> #include <linux/cpuhotplug.h> +#ifndef __GENKSYMS__ +#include <linux/tick.h> +#endif struct device; struct device_node; @@ -163,7 +166,7 @@ static inline int suspend_disable_secondary_cpus(void) { int cpu = 0; - if (IS_ENABLED(CONFIG_PM_SLEEP_SMP_NONZERO_CPU)) + if (support_cpu0_nohz_full && IS_ENABLED(CONFIG_PM_SLEEP_SMP_NONZERO_CPU)) cpu = -1; return freeze_secondary_cpus(cpu); diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index d7bc1358af79..9e829ec93c2f 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -559,7 +559,7 @@ void __init tick_nohz_init(void) } if (IS_ENABLED(CONFIG_PM_SLEEP_SMP) && - !IS_ENABLED(CONFIG_PM_SLEEP_SMP_NONZERO_CPU)) { + (!support_cpu0_nohz_full || !IS_ENABLED(CONFIG_PM_SLEEP_SMP_NONZERO_CPU))) { cpu = smp_processor_id(); if (cpumask_test_cpu(cpu, tick_nohz_full_mask)) { -- 2.30.0
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9NR7Q CVE: NA -------------------------------- Enable CONFIG_PM_SLEEP_SMP_NONZERO_CPU and CONFIG_ARCH_SUSPEND_NONZERO_CPU. Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> --- arch/arm64/configs/openeuler_defconfig | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/configs/openeuler_defconfig b/arch/arm64/configs/openeuler_defconfig index 34061d75a0d2..b404f64278f0 100644 --- a/arch/arm64/configs/openeuler_defconfig +++ b/arch/arm64/configs/openeuler_defconfig @@ -581,6 +581,7 @@ CONFIG_HIBERNATION_SNAPSHOT_DEV=y CONFIG_PM_STD_PARTITION="" CONFIG_PM_SLEEP=y CONFIG_PM_SLEEP_SMP=y +CONFIG_PM_SLEEP_SMP_NONZERO_CPU=y # CONFIG_PM_AUTOSLEEP is not set # CONFIG_PM_WAKELOCKS is not set CONFIG_PM=y @@ -599,6 +600,7 @@ CONFIG_CPU_PM=y CONFIG_ARCH_HIBERNATION_POSSIBLE=y CONFIG_ARCH_HIBERNATION_HEADER=y CONFIG_ARCH_SUSPEND_POSSIBLE=y +CONFIG_ARCH_SUSPEND_NONZERO_CPU=y # end of Power management options # -- 2.30.0
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