问题：这个 dmesg 是什么意思？是不是坏了？两年前的帖子这可能意味着 I/O 性能下降，这可能是/仍然是真的吗？
背景：我遇到了 I/O 性能下降的问题，但我认为这是因为我在主板上使用内置 RAID，而不是专用卡。我一直在追踪一些随机的内核消息，现在我切换到桌面——更多的是出于好奇。该机箱配有 Intel Core i7 930 处理器。以下消息会定期出现。我正在运行 openPBS，如果这很重要的话。但自从系统重新启动以来，这些消息在过去一天半内出现了六次。
的输出uname -a为：
Linux ###### 2.6.32-26-generic #48-Ubuntu SMP 2010 年 11 月 24 日星期三 10:14:11 UTC x86_64 GNU/Linux
来自以下的消息dmesg：
[ 185.609169] CPU0 attaching NULL sched-domain.
[ 185.609173] CPU1 attaching NULL sched-domain.
[ 185.609175] CPU2 attaching NULL sched-domain.
[ 185.609176] CPU3 attaching NULL sched-domain.
[ 185.609178] CPU4 attaching NULL sched-domain.
[ 185.609179] CPU5 attaching NULL sched-domain.
[ 185.609180] CPU6 attaching NULL sched-domain.
[ 185.609182] CPU7 attaching NULL sched-domain.
[ 185.756764] CPU0 attaching sched-domain:
[ 185.756766] domain 0: span 0,7 level SIBLING
[ 185.756768] groups: 0 (cpu_power = 589) 7 (cpu_power = 589)
[ 185.756772] domain 1: span 0-7 level MC
[ 185.756773] groups: 0,7 (cpu_power = 1178) 1,4 (cpu_power = 1178) 2,5 (cpu_power = 1178) 3,6 (cpu_power = 1178)
[ 185.756780] CPU1 attaching sched-domain:
[ 185.756781] domain 0: span 1,4 level SIBLING
[ 185.756782] groups: 1 (cpu_power = 589) 4 (cpu_power = 589)
[ 185.756786] domain 1: span 0-7 level MC
[ 185.756787] groups: 1,4 (cpu_power = 1178) 2,5 (cpu_power = 1178) 3,6 (cpu_power = 1178) 0,7 (cpu_power = 1178)
[ 185.756793] CPU2 attaching sched-domain:
[ 185.756794] domain 0: span 2,5 level SIBLING
[ 185.756795] groups: 2 (cpu_power = 589) 5 (cpu_power = 589)
[ 185.756799] domain 1: span 0-7 level MC
[ 185.756800] groups: 2,5 (cpu_power = 1178) 3,6 (cpu_power = 1178) 0,7 (cpu_power = 1178) 1,4 (cpu_power = 1178)
[ 185.756806] CPU3 attaching sched-domain:
[ 185.756807] domain 0: span 3,6 level SIBLING
[ 185.756808] groups: 3 (cpu_power = 589) 6 (cpu_power = 589)
[ 185.756812] domain 1: span 0-7 level MC
[ 185.756813] groups: 3,6 (cpu_power = 1178) 0,7 (cpu_power = 1178) 1,4 (cpu_power = 1178) 2,5 (cpu_power = 1178)
[ 185.756819] CPU4 attaching sched-domain:
[ 185.756820] domain 0: span 1,4 level SIBLING
[ 185.756821] groups: 4 (cpu_power = 589) 1 (cpu_power = 589)
[ 185.756825] domain 1: span 0-7 level MC
[ 185.756826] groups: 1,4 (cpu_power = 1178) 2,5 (cpu_power = 1178) 3,6 (cpu_power = 1178) 0,7 (cpu_power = 1178)
[ 185.756832] CPU5 attaching sched-domain:
[ 185.756833] domain 0: span 2,5 level SIBLING
[ 185.756834] groups: 5 (cpu_power = 589) 2 (cpu_power = 589)
[ 185.756838] domain 1: span 0-7 level MC
[ 185.756839] groups: 2,5 (cpu_power = 1178) 3,6 (cpu_power = 1178) 0,7 (cpu_power = 1178) 1,4 (cpu_power = 1178)
[ 185.756845] CPU6 attaching sched-domain:
[ 185.756846] domain 0: span 3,6 level SIBLING
[ 185.756847] groups: 6 (cpu_power = 589) 3 (cpu_power = 589)
[ 185.756850] domain 1: span 0-7 level MC
[ 185.756852] groups: 3,6 (cpu_power = 1178) 0,7 (cpu_power = 1178) 1,4 (cpu_power = 1178) 2,5 (cpu_power = 1178)
[ 185.756858] CPU7 attaching sched-domain:
[ 185.756859] domain 0: span 0,7 level SIBLING
[ 185.756860] groups: 7 (cpu_power = 589) 0 (cpu_power = 589)
[ 185.756863] domain 1: span 0-7 level MC
[ 185.756865] groups: 0,7 (cpu_power = 1178) 1,4 (cpu_power = 1178) 2,5 (cpu_power = 1178) 3,6 (cpu_power = 1178)
答案1
该消息只是告诉您 CPU 核心正在初始化为空域。您可以根据需要关闭该消息，但这不会对您的 I/O 造成任何损害。
您可以使用它iostat来查找您的 IO 中的问题以及该错误中发生的情况。
如果可以，请安装ubuntu-desktop软件包，注销并登录 gnome，看看是否遇到同样的问题。这将从系统范围的 io 问题中分离出 kio 和 kthread 问题。对两者运行测试。
答案2
使用以下命令明确禁用并启用 CPU 核心后，我的日志中出现了相同的消息：
echo 0 > /sys/devices/system/cpu/cpu6/online
echo 1 > /sys/devices/system/cpu/cpu6/online
我的建议是，如果您收到此消息，请尝试按照上述方法循环禁用和启用 CPU 核心。