Linux 60秒快速性能分析操作手册(3)

Linux

一个较高的 15分钟负载与一个较低的1分钟负载同时出现，可能意味着已经错过了问题发生的现场。

┌──[root@vms100.liruilongs.github.io]-[~]
└─$uptime
 11:33:45 up 35 min,  1 user,  load average: 1.39, 6.06, 11.64
┌──[root@vms100.liruilongs.github.io]-[~]
└─$ 

dmesg | tail或者cat /var/log/messages

或者 journalctl -k | tail 也可以结合 cat /var/log/messages 来排查

┌──[liruilong@liruilongs.github.io]-[~]
└─$dmesg | tail
[   12.216869] vmwgfx 0000:00:0f.0: [drm] Available shader model: SM_5.
[   12.225954] [drm] Initialized vmwgfx 2.20.0 20211206 for 0000:00:0f.0 on minor 0
[   12.233005] Bluetooth: hci0: unexpected cc 0x0c12 length: 2 < 3
[   12.233011] Bluetooth: hci0: Opcode 0x c12 failed: -38
[   12.238757] fbcon: vmwgfxdrmfb (fb0) is primary device
[   12.248762] Console: switching to colour frame buffer device 160x50
[   12.269448] vmwgfx 0000:00:0f.0: [drm] fb0: vmwgfxdrmfb frame buffer device
[   14.350586] block dm-0: the capability attribute has been deprecated.
[   14.446480] block nvme0n1: No UUID available providing old NGUID
[   14.498286] block nvme0n1: No UUID available providing old NGUID

这个命令显示过去 10 条系统日志，如果有的话。注意在这里寻找可能导致性能问题的错误。 添加 T和t 可以展示对应的时间

┌──[root@vms100.liruilongs.github.io]-[~]
└─$dmesg -T| tail
[日 1月 14 10:58:57 2024] vmxnet3 0000:1b:00.0 ens256: NIC Link is Up 10000 Mbps
[日 1月 14 10:59:38 2024] device ovs-system entered promiscuous mode
[日 1月 14 10:59:39 2024] Timeout policy base is empty
[日 1月 14 10:59:39 2024] Failed to associated timeout policy `ovs_test_tp'
[日 1月 14 10:59:40 2024] device br-tun entered promiscuous mode
[日 1月 14 10:59:40 2024] device br-int entered promiscuous mode
[日 1月 14 10:59:40 2024] device ens224 entered promiscuous mode
[日 1月 14 10:59:40 2024] device br-ex entered promiscuous mode
[日 1月 14 11:03:14 2024] capability: warning: `privsep-helper' uses deprecated v2 capabilities in a way that may be insecure
[日 1月 14 11:04:34 2024] hrtimer: interrupt took 11973872 ns
┌──[root@vms100.liruilongs.github.io]-[~]
└─$

在日常维护中，往往结合 grep 快速定位问题

┌──[root@liruilongs.github.io]-[~]
└─$ dmesg -T | grep -i error
[五 11月 10 10:32:57 2023] BERT: Boot Error Record Table support is disabled. Enable it by using bert_enable as kernel parameter.
┌──[root@liruilongs.github.io]-[~]
└─$ dmesg -T | grep -i warn
[五 11月 10 10:32:54 2023] Warning: Intel Processor - this hardware has not undergone upstream testing. Please consult http://wiki.centos.org/FAQ for more information
┌──[root@liruilongs.github.io]-[~]
└─$