sth about linux

  1. 查看Linux系统的性能数据，可以从procfs文件中获得cat /proc/stat .其内包含了系统的基本信息，包括CPU、运行情况、中断、IO等。

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    # cat /proc/stat
    cpu  2475801 26920 1543326 831255053 126353 0 8014 0 0 0
    cpu0 1200337 13938 770224 415719375 48294 0 4445 0 0 0
    cpu1 1275464 12981 773101 415535678 78058 0 3569 0 0 0
    intr 3162925830 0 9 0 0 1257 0 3 0 0 0 0 34 15 0 0 0 0 0 0 0 0 0 0 0 0 50 0 4238742 0 1802026 2956565 1456602 992957 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
    ctxt 5997613057
    btime 1697473419
    processes 298842
    procs_running 1
    procs_blocked 0
    softirq 783883930 0 284012127 16 7265487 4208089 0 37801 284186406 19679 204154325

  2. 打印当前CPU在执行的内容echo "l" > /proc/sysrq-trigger

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    #dmesg -T

    [Mon Dec  4 11:23:21 2023] sysrq: Show backtrace of all active CPUs
    [Mon Dec  4 11:23:21 2023] NMI backtrace for cpu 0
    [Mon Dec  4 11:23:21 2023] CPU: 0 PID: 298644 Comm: bash Tainted: G           OE     5.4.0-162-generic #179-Ubuntu
    [Mon Dec  4 11:23:21 2023] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 449e491 04/01/2014
    [Mon Dec  4 11:23:21 2023] Call Trace:
    [Mon Dec  4 11:23:21 2023]  dump_stack+0x6d/0x8b
    [Mon Dec  4 11:23:21 2023]  ? lapic_can_unplug_cpu+0x80/0x80
    [Mon Dec  4 11:23:21 2023]  nmi_cpu_backtrace.cold+0x14/0x53
    [Mon Dec  4 11:23:21 2023]  nmi_trigger_cpumask_backtrace+0xe8/0xf0
    [Mon Dec  4 11:23:21 2023]  arch_trigger_cpumask_backtrace+0x19/0x20
    [Mon Dec  4 11:23:21 2023]  sysrq_handle_showallcpus+0x17/0x20
    [Mon Dec  4 11:23:21 2023]  __handle_sysrq.cold+0x48/0x107
    [Mon Dec  4 11:23:21 2023]  write_sysrq_trigger+0x28/0x40
    [Mon Dec  4 11:23:21 2023]  proc_reg_write+0x43/0x70
    [Mon Dec  4 11:23:21 2023]  __vfs_write+0x1b/0x40
    [Mon Dec  4 11:23:21 2023]  vfs_write+0xb9/0x1a0
    [Mon Dec  4 11:23:21 2023]  ksys_write+0x67/0xe0
    [Mon Dec  4 11:23:21 2023]  __x64_sys_write+0x1a/0x20
    [Mon Dec  4 11:23:21 2023]  do_syscall_64+0x57/0x190
    [Mon Dec  4 11:23:21 2023]  entry_SYSCALL_64_after_hwframe+0x5c/0xc1
    [Mon Dec  4 11:23:21 2023] RIP: 0033:0x7fbb5987c077
    [Mon Dec  4 11:23:21 2023] Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
    [Mon Dec  4 11:23:21 2023] RSP: 002b:00007ffff3a8dae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
    [Mon Dec  4 11:23:21 2023] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fbb5987c077
    [Mon Dec  4 11:23:21 2023] RDX: 0000000000000002 RSI: 00005560583b0020 RDI: 0000000000000001
    [Mon Dec  4 11:23:21 2023] RBP: 00005560583b0020 R08: 000000000000000a R09: 0000000000000001
    [Mon Dec  4 11:23:21 2023] R10: 0000556056fc9017 R11: 0000000000000246 R12: 0000000000000002
    [Mon Dec  4 11:23:21 2023] R13: 00007fbb5995b6a0 R14: 00007fbb599574a0 R15: 00007fbb599568a0
    [Mon Dec  4 11:23:21 2023] Sending NMI from CPU 0 to CPUs 1:
    [Mon Dec  4 11:23:21 2023] NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10


  3. 向内核中输出内容echo "sth " > /dev/kmsg

  4. 查看procfs文件的描述信息 man procfs