内核消息‘the 0附加空sched-domain.’意味着什么？

Question

问:这个dmesg是什么意思？是不是很糟？有一个关于这可能意味着降低I/O性能的两岁职位，这是否仍然是真的？

背景:我已经经历了退化的I/O，但我认为这是由于我的主板上使用内置的RAID，而不是专用卡。我一直在追踪几个随机的内核消息，现在我切换到了我的桌面--更多的是出于好奇，而不是任何事情。这个盒子有一个英特尔核心i7 930处理器。以下消息的出现具有一定的规律性。如果这重要的话，我正在运行openPBS。但在系统重新启动后的过去一天半内，这些消息出现了六次。

uname -a的输出是：

###### 2.6.32-26-通用#48-Ubuntu 11月24日10:14:11 UTC 2010 x86_64 GNU/Linux

来自dmesg的消息是：

[  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)

Answer 1

消息只是告诉您CPU核心正在初始化为空域。如果您愿意，可以关闭消息，但这不会对您的I/O造成损害。

您可以使用iostat来查找IO中的问题，以及在这个bug中发生了什么。

如果可以的话，安装ubuntu-desktop包，注销并登录到gnome，看看是否遇到了同样的问题。这将将kio和k线程问题从系统范围的io问题中分离出来。对这两种情况进行测试。

Answer 2

在显式禁用和启用CPU核心之后，相同的消息出现在我的日志中：

echo 0 > /sys/devices/system/cpu/cpu6/online
echo 1 > /sys/devices/system/cpu/cpu6/online

我的建议是，如果您收到这条消息，试着循环通过禁用和启用CPU核心如上所述。