Messages in this thread Patch in this message | | | From | Feng Tang <> | Subject | [Patch v2 1/2] smp: Add helper function to mark possible bad package number | Date | Tue, 13 Jun 2023 13:25:22 +0800 |
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For some architecture like x86, it calculates processor package number in the process of bringing up all CPUs. The 'nr_cpus=' and 'maxcpus=' cmdline parameter setup may reduce the number of CPUs which actually get brought up, and make the package number inaccurate (less than the real number).
Add a general helper function arch_mark_bad_package_count() to enable affected architectures to mark the possible unreliable package estimation. Also implement the support in x86 to leverage it.
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Feng Tang <feng.tang@intel.com> --- arch/x86/kernel/smpboot.c | 9 +++++++++ include/linux/smp.h | 13 +++++++++++++ kernel/smp.c | 10 +++++++++- 3 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 352f0ce1ece4..b78770b0c43d 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1274,6 +1274,15 @@ void arch_disable_smp_support(void) disable_ioapic_support(); } +void arch_mark_bad_package_count(char *reason) +{ + if (package_count_unreliable) + return; + + package_count_unreliable = true; + pr_warn("Processor package count may be unreliable due to: %s\n", reason); +} + /* * Fall back to non SMP mode after errors. * diff --git a/include/linux/smp.h b/include/linux/smp.h index 91ea4a67f8ca..25bfdc73cc78 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -188,6 +188,13 @@ static inline int get_boot_cpu_id(void) return __boot_cpu_id; } +extern bool package_count_unreliable; + +static inline bool is_package_count_reliable(void) +{ + return !package_count_unreliable; +} + #else /* !SMP */ static inline void smp_send_stop(void) { } @@ -230,6 +237,10 @@ static inline int get_boot_cpu_id(void) return 0; } +static inline bool is_package_count_reliable(void) +{ + return true; +} #endif /* !SMP */ /** @@ -283,6 +294,8 @@ extern void arch_disable_smp_support(void); extern void arch_thaw_secondary_cpus_begin(void); extern void arch_thaw_secondary_cpus_end(void); +extern void arch_mark_bad_package_count(char *reason); + void smp_setup_processor_id(void); int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, diff --git a/kernel/smp.c b/kernel/smp.c index ab3e5dad6cfe..494288bedd9b 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -904,13 +904,20 @@ static int __init nosmp(char *str) early_param("nosmp", nosmp); +bool package_count_unreliable; + +void __weak arch_mark_bad_package_count(char *reason) { } + /* this is hard limit */ static int __init nrcpus(char *str) { int nr_cpus; - if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids) + if (get_option(&str, &nr_cpus) && nr_cpus > 0 && + nr_cpus < nr_cpu_ids) { set_nr_cpu_ids(nr_cpus); + arch_mark_bad_package_count("'nr_cpus' setup"); + } return 0; } @@ -923,6 +930,7 @@ static int __init maxcpus(char *str) if (setup_max_cpus == 0) arch_disable_smp_support(); + arch_mark_bad_package_count("'maxcpus' setup"); return 0; } -- 2.34.1
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