dmesg(diagnostic message)
dmesg命令被用于检查和控制内核的环形缓冲区。kernel会将开机信息存储在ring buffer中。您若是开机时来不及查看信息,可利用dmesg来查看。开机信息保存在/var/log/dmesg文件里。
参数
-c:显示信息后,清除ring buffer中的内容;
-s<缓冲区大小>:预设置为8196,刚好等于ring buffer的大小;
-n:设置记录信息的层级。
例子
:dmesg | head
[ 0.000000] Linux version 4.15.0-88-generic (buildd@lgw01-amd64-036) (gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)) #88-Ubuntu SMP Tue Feb 11 20:11:34 UTC 2020 (Ubuntu 4.15.0-88.88-generic 4.15.18)
[ 0.000000] Command line:
[ 0.000000] KERNEL supported cpus:
[ 0.000000] Intel GenuineIntel
[ 0.000000] AMD AuthenticAMD
[ 0.000000] Centaur CentaurHauls
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x008: 'MPX bounds registers'
查看IO支持的调度:
:dmesg | grep -i scheduler
[ 0.571636] io scheduler noop registered
[ 0.571637] io scheduler deadline registered
[ 0.571654] io scheduler cfq registered (default)