飞鱼博客购买的服务器写的内存是 2GB,但是从宝塔看只用 1800 多 MB...
先用free看一下:
- total used free shared buff/cache available
- Mem: 1882000 422140 682784 776 777076 1283632
- Swap: 1049596 40448 1009148
查看内核预留内存:dmesg | grep -i memory
- [ 0.000000] Base memory trampoline at [ffff9eb200099000] 99000 size 24576
- [ 0.000000] Reserving 161MB of memory at 688MB for crashkernel (System RAM: 2047MB)
- [ 0.000000] Early memory node ranges
- [ 0.000000] PM: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
- [ 0.000000] PM: Registered nosave memory: [mem 0x000a0000-0x000effff]
- [ 0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]
- [ 0.000000] Memory: 1858740k/2097008k available (7788k kernel code, 392k absent, 237876k reserved, 5954k data, 1984k init)
- [ 0.000000] please try 'cgroup_disable=memory' option if you don't want memory cgroups
- [ 0.331747] Initializing cgroup subsys memory
- [ 0.475802] x86/mm: Memory block size: 128MB
- [ 1.231809] Freeing initrd memory: 20320k freed
- [ 1.349328] Non-volatile memory driver v1.3
- [ 1.352113] crash memory driver: version 1.1
- [ 1.498955] Freeing unused kernel memory: 1984k freed
- [ 1.502904] Freeing unused kernel memory: 392k freed
- [ 1.505199] Freeing unused kernel memory: 536k freed
- [ 2.262990] [TTM] Zone kernel: Available graphics memory: 941000 kiB
crashkernel保留了161MB的内存，属于kdump服务.
注意:kdump 是在系统崩溃、死锁或者死机的时候用来转储内存运行参数的一个工具和服务。打个比方，如果系统一旦崩溃那么正常的内核就没有办法工作了，在这个时候将由 kdump 产生一个用于 capture 当前运行信息的内核，该内核会将此时的内存中的所有运行状态和数据信息收集到一个 dump core 文件中以便于工程师分析崩溃原因，一旦内存信息收集完成，系统将自动重启。
停止并关闭kdump
- systemctl stop kdump
- systemctl disable kdump
修改grub文件(宝塔直接在线改就好)
- vi /etc/default/grub
将crashkernel=auto改为crashkernel=0
如:
- GRUB_TIMEOUT=5#请无视本行
- GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"#请无视本行
- GRUB_DEFAULT=saved#请无视本行
- GRUB_DISABLE_SUBMENU=true#请无视本行
- GRUB_TERMINAL_OUTPUT="console"#请无视本行
- GRUB_CMDLINE_LINUX="crashkernel=0 resume=UUID=XXXX-XXXX-XXXX-XXXX-XXXX" #改动此行
- GRUB_DISABLE_RECOVERY="true"#请无视本行
- GRUB_ENABLE_BLSCFG=true#请无视本行
更新grub配置文件、重启系统
- grub2-mkconfig -o /boot/grub2/grub.cfg
- reboot
你就会发现内存变多了..
