网站开发开源框架,动漫网站建站,网络商务,网站规划与建设策划书在内核中#xff0c;有几个位图变量是用作标识cpu数量和状态的#xff0c;它们分别是#xff1a;
变量名称用途循环所使用的宏cpu_possible_mask系统中有多少个可以运行的cpu核for_each_possible_cpucpu_present_mask系统中有多少个可处于运行状态的cpu核for_each_present_…在内核中有几个位图变量是用作标识cpu数量和状态的它们分别是
变量名称用途循环所使用的宏cpu_possible_mask系统中有多少个可以运行的cpu核for_each_possible_cpucpu_present_mask系统中有多少个可处于运行状态的cpu核for_each_present_cpucpu_online_mask系统中有多少个正在工作的cpu核for_each_online_cpucpu_active_mask系统中有多少个活跃的cpu核
本文主要介绍一下cpu_possible_mask和cpu_present_mask的初始化。
1 cpu_possible_mask的初始化过程
start_kernel -- setup_arch -- smp_init_cpus -- acpi_parse_and_init_cpus smp_cpu_setup --set_cpu_possible
从上述过程中内核从acpi中获取了可以运行的cpu的数量。
2cpu_present_mask
start_kernel --reset_init -- kernel_thread(kernel_thread) kernel_init(thread) --kernel_init_freeable --smp_prepare_cpus --cpu_prepare --cpu_psci_cpu_prepare --set_cpu_present --smp_init --cpu_up --cpu_psci_cpu_boot
还是从start_kernel开始这个时候cpu0已经启动完成内核创建了一个线程kernel_init其余的cpu和在这个函数里进行初始化工作。
内核首先根据cpu_possible_mask中的信息为每一个possible cpu调用cpu_prepare得到了固件的回复后将该cpu设置到cpu_present_mask相对应的位置上这样系统就获得了可以运行的cpu的位图。
然后内核调用smp_init--cpu_up逐一初始化这些内核关于这些内核的的启动流程可以参考我的另一篇博客
smp_init过程解析_slab_prepare_cpu-CSDN博客 为什么想到要看这两个变量的初始化呢原因是最近正在处理的项目是一个双cpu的服务器每个服务器有32个核但我们无论是在GUI的系统信息里还是在dmidecode中得到的信息都是一个64核的cpu其中dmidecode信息如下
dmidecode -r processor# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 3.3.0 present.
# SMBIOS implementations newer than version 3.2.0 are not
# fully supported by this version of dmidecode.Handle 0x0008, DMI type 4, 48 bytes
Processor InformationSocket Designation: SOCKET 0Type: Central ProcessorFamily: ARMManufacturer: PHYTIUM LTDID: 10 08 00 00 00 00 00 00Signature: Implementor 0x00, Variant 0x0, Architecture 0, Part 0x081, Revision 0Version: Phytium S5000C 64 CoreVoltage: 0.9 VExternal Clock: UnknownMax Speed: 2300 MHzCurrent Speed: 2300 MHzStatus: Populated, EnabledUpgrade: NoneL1 Cache Handle: 0x0005L2 Cache Handle: 0x0006L3 Cache Handle: 0x0007Serial Number: KAP8160405050000Asset Tag: Not SetPart Number: Not SetCore Count: 64Core Enabled: 64Thread Count: 64Characteristics:64-bit capableMulti-CoreExecute ProtectionEnhanced Virtualization
一开始以为是cpu_possible_mask或者cpu_present_mask有误但根据dmidecode的源码分析后看到这些信息是从内核的文件/sys/firmware/dmi/tables/smbios_entry_point中获取dmidecode的过程如下见dmidecode.c
static void dmi_decode(const struct dmi_header *h, u16 ver)
{const u8 *data h-data;/** Note: DMI types 37 and 42 are untested*/switch (h-type){case 0: /* 7.1 BIOS Information */......case 4: /* 7.5 Processor Information */printf(Processor Information\n);if (h-length 0x1A) break;printf(\tSocket Designation: %s\n,dmi_string(h, data[0x04]));printf(\tType: %s\n,dmi_processor_type(data[0x05]));printf(\tFamily: %s\n,dmi_processor_family(h, ver));printf(\tManufacturer: %s\n,dmi_string(h, data[0x07]));dmi_processor_id(h, \t);printf(\tVersion: %s\n,dmi_string(h, data[0x10]));printf(\tVoltage:);dmi_processor_voltage(data[0x11]);printf(\n);printf(\tExternal Clock: );dmi_processor_frequency(data 0x12);printf(\n);printf(\tMax Speed: );dmi_processor_frequency(data 0x14);printf(\n);printf(\tCurrent Speed: );dmi_processor_frequency(data 0x16);printf(\n);if (data[0x18] (1 6))printf(\tStatus: Populated, %s\n,dmi_processor_status(data[0x18] 0x07));elseprintf(\tStatus: Unpopulated\n);printf(\tUpgrade: %s\n,dmi_processor_upgrade(data[0x19]));if (h-length 0x20) break;if (!(opt.flags FLAG_QUIET)){printf(\tL1 Cache Handle:);dmi_processor_cache(WORD(data 0x1A), L1, ver);printf(\n);printf(\tL2 Cache Handle:);dmi_processor_cache(WORD(data 0x1C), L2, ver);printf(\n);printf(\tL3 Cache Handle:);dmi_processor_cache(WORD(data 0x1E), L3, ver);printf(\n);}if (h-length 0x23) break;printf(\tSerial Number: %s\n,dmi_string(h, data[0x20]));printf(\tAsset Tag: %s\n,dmi_string(h, data[0x21]));printf(\tPart Number: %s\n,dmi_string(h, data[0x22]));if (h-length 0x28) break;if (data[0x23] ! 0)printf(\tCore Count: %u\n,h-length 0x2C data[0x23] 0xFF ?WORD(data 0x2A) : data[0x23]);if (data[0x24] ! 0)printf(\tCore Enabled: %u\n,h-length 0x2E data[0x24] 0xFF ?WORD(data 0x2C) : data[0x24]);if (data[0x25] ! 0)printf(\tThread Count: %u\n,h-length 0x30 data[0x25] 0xFF ?WORD(data 0x2E) : data[0x25]);printf(\tCharacteristics:);dmi_processor_characteristics(WORD(data 0x26), \t\t);break;......。
cpu的信息包括socket都在dmicode信息中。
dmi信息在内核中的处理是在driver/firmware/dmi_scan.c中代码如下
void __init dmi_scan_machine(void)
{char __iomem *p, *q;char buf[32];if (efi_enabled(EFI_CONFIG_TABLES)) {if (efi.smbios3 ! EFI_INVALID_TABLE_ADDR) {p dmi_early_remap(efi.smbios3, 32);......
dmidecode这些信息是由efi写到内存的efi.smbios3地址中内核使用iomap将该地址映射到内核的虚拟地址空间并且读出来放到了/sys/firmware/dmi/tables/smbios_entry_point中工具dmidecode对其进行读取和解析。
所以这个问题是smbios信息有误更新后就可以显示正确的信息了。
dmidecode的源码在如下地址
Index of /releases/dmidecode/
