在一个CentOS8系统的VPS上，free显示不对，有1G内存但是只显示了818MB，少了200多MB
total used free shared buff/cache available
Mem: 818 87 453 7 277 597
Swap: 1023 0 1023
1、使用dmidecode命令查看linux硬件信息
dmidecode -t memory
# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 2.8 present.
Handle 0x1000, DMI type 16, 23 bytes
Physical Memory Array
Location: Other
Use: System Memory
Error Correction Type: Multi-bit ECC
Maximum Capacity: 1 GB
Error Information Handle: Not Provided
Number Of Devices: 1
Handle 0x1100, DMI type 17, 40 bytes
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: 1 GB
Form Factor: DIMM
Set: None
Locator: DIMM 0
Bank Locator: Not Specified
Type: RAM
Type Detail: Other
Speed: Unknown
Manufacturer: Red Hat
Serial Number: Not Specified
Asset Tag: Not Specified
Part Number: Not Specified
Rank: Unknown
Configured Memory Speed: Unknown
Minimum Voltage: Unknown
Maximum Voltage: Unknown
Configured Voltage: Unknown