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Different Memory Utilization between CLI and Dashboard Grid Master

Techie
Posts: 4
128     0

Hi Members,

 

 

why the Utilization of Memory  from CLI and Dashboard grid master is different?

I'm using NIOS 8.3.0

 

>show memory 
              total            used           free           buffers         cached
Mem:     8047448     6956216      1091232   187700         1640184
Swap:    8388604     38956          8349648
Total:    16436052    6995172      9440880

----------------------------------------------------

> show cpu
--------------------memory------------------------       ---swap--   -----io-------------- --system-- ----cpu----
swpd     free           idle         buff         cache       si     so       bi       bo                 in cs         us sy id  wa st
38956   3063000    1079756 187700    1795544    0     0        0        13                   0 0           2  1   97 0   0

-------------------------------------------------------------------------------------------------------------------

but when I check from the dashboard Grid master I just see Memory Usage is 25%.

 

 

Thanks for answer

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Re: Different Memory Utilization between CLI and Dashboard Grid Master

Authority
Posts: 18
129     0

This is expected because of the way NIOS handles memory. The CLI command does not show the actual memory utilization, what you see in GUI is accurate. See below for more details

 

----------------------------------

The memory utilization dashboard widget is different from that which is shown when executing the "show memory" command on the CLI of NIOS appliance. The calculations done for each respective value differ. Furthermore, with the move to the usage of HugePages in 8.1.6, the derivation of the dashboard memory utilization widget value is less obvious.

**Note the memory utilization dashboard widget and the value of the ibSystemMonitorMemUsage (OID: 1.3.6.1.4.1.7779.3.1.1.2.1.8.2.1) are the same value and calculated in the same manner.

 

 

Prior to NIOS 8.1.6, the calculation of free memory is:

freeMem = MemFree + cachedMemory + bufferMemory + slabMemory


From NIOS 8.1.6 and beyone the calculation of free memory is:

freeMem = MemFree + cachedMemory + bufferMemory + slabMemory + (hugePages * hugePageSize)


In all cases, the memory utilization value is calculated as such:

MemUsed = ((TotalMem - freeMem)/TotalMem)*100

 

 

The show memory command displays the following information:

Infoblox > show memory

total used free buffers cached

Mem: 12176268 10947772 1228496 284024 3538472

Swap: 12582908 0 12582908

Total: 24759176 10947772 13811404


The slab and HugePages information is missing from the ouput just above. Therefore, it is not possible to perform the calculation to match the Dashboard Memory Utilization value using this output.

Before 8.1.6, the only value missing was slab, which tends to be a small value. One can get a close approximation without having the slab memory number for pre-8.1.6 systems.

After 8.1.6, HugePages are used and are a significant value. Additionally, the cache memory value decreases in part because of the usage of HugePages.

**Note: In the Linux kernel, cached memory includes shared memory. What was before considered to be shared memory is now part of the HugePages allocation. Decreasing shared memory, decreases cached memory and would therefore, make the calculation using the "show memory" output inaccurate by a larger margin.

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Re: Different Memory Utilization between CLI and Dashboard Grid Master

Techie
Posts: 4
129     0

 

Thank You Jrajan for explaining about the calculation of memory in infoblox.

 

I Understand now.

 

 

 

 

 

Regards,

 

Ricki S

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