linux – SNMP内存值与`free`不匹配

比较一下

# free -m
             total       used       free     shared    buffers     cached
Mem:         72363      68035       4328          0        522      66294
-/+ buffers/cache:       1218      71145
Swap:        12291          0      12291

还有这个：

# snmpwalk -c public -v 2c localhost .1.3.6.1.4.1.2021.4
UCD-SNMP-MIB::memIndex.0 = INTEGER: 0
UCD-SNMP-MIB::memErrorName.0 = STRING: swap
UCD-SNMP-MIB::memTotalSwap.0 = INTEGER: 12586888 kB
UCD-SNMP-MIB::memAvailSwap.0 = INTEGER: 12586784 kB
UCD-SNMP-MIB::memTotalReal.0 = INTEGER: 74100516 kB
UCD-SNMP-MIB::memAvailReal.0 = INTEGER: 4429580 kB
UCD-SNMP-MIB::memTotalFree.0 = INTEGER: 17016364 kB
UCD-SNMP-MIB::memMinimumSwap.0 = INTEGER: 16000 kB
UCD-SNMP-MIB::memBuffer.0 = INTEGER: 534804 kB
UCD-SNMP-MIB::memCached.0 = INTEGER: 44238560 kB
UCD-SNMP-MIB::memSwapError.0 = INTEGER: noError(0)
UCD-SNMP-MIB::memSwapErrorMsg.0 = STRING:

为什么免费显示66294MB用于“缓存”,而snmp显示大约44238MB用于“memCached”？那应该不一样吗？

看看MIB我发现“memCached”是用于缓存的“物理或虚拟”内存. (不要告诉我它将磁盘缓存放入交换中)^^

目标是通过snmp找出真正的自由物理内存(即此处为免费显示的71145).

更多信息

# cat /proc/meminfo
MemTotal:     74100516 kB
MemFree:       4422092 kB
Buffers:        542168 kB
Cached:       44239460 kB
SwapCached:          4 kB
Active:       16455504 kB
Inactive:     28707308 kB
SwapTotal:    12586888 kB
SwapFree:     12586784 kB
Dirty:            2536 kB
Writeback:           0 kB
AnonPages:      381088 kB
Mapped:         252132 kB
Slab:         23961488 kB
SReclaimable: 23648768 kB
SUnreclaim:     312720 kB
PageTables:       7812 kB
NFS_Unstable:        0 kB
Bounce:              0 kB
WritebackTmp:        0 kB
CommitLimit:  49637144 kB
Committed_AS:        4 kB
VmallocTotal: 34359738367 kB
VmallocUsed:    264124 kB
VmallocChunk: 34359474191 kB
HugePages_Total:     0
HugePages_Free:      0
HugePages_Rsvd:      0
HugePages_Surp:      0
Hugepagesize:     2048 kB
DirectMap4k:      7936 kB
DirectMap2M:  75481088 kB

解决方法

从免费的联机帮助页(1)：

cache Memory used by the page cache and slabs (Cached and Slab in /proc/meminfo)

free包括缓存中的slab分配; UCD-SNMP-MIB没有.如果你添加slab分配,你会得到：

UCD-SNMP-MIB::memCached.0 + slab = 44238560 + 23961488
                                 = 68200048 KB

这更接近免费报道(67885056 KB).

至于获得真正的自由物理内存,使用此MIB可以做的最好的事情是粗略估计：

totFree = memAvailReal.0 + memBuffer.0 + memCached.0
        = 4429580        + 534804      + 44238560
        = 49202944 KB

这仍然明显低于免费报告的空闲缓冲区/缓存的值.

请注意,HOST-RESOURCES-MIB并不是更好;请参阅my answer到Stack Overflow上的类似问题.

较新的内核实际上为此提供了更好的指标.再次从free(1)手册页：

available

Estimation of how much memory is available for starting new applications,without swapping. Unlike the data provided by the cache or free fields,this field takes into account page cache and also that not all reclaimable memory slabs will be reclaimed due to items being in use (MemAvailable in /proc/meminfo,available on kernels 3.14,emulated on kernels 2.6.27+,otherwise the same as free)

这个值将低于可用缓冲区/缓存的总和,并且可以更好地衡量可用内存,但我没有在/ proc / meminfo中看到它并且我没有找到使用它的MIB.

原文链接：https://www.f2er.com/linux/396547.html

linux – SNMP内存值与`free`不匹配

解决方法

猜你在找的Linux相关文章